1 /*
2 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/compile.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/convertnode.hpp"
35 #include "opto/loopnode.hpp"
36 #include "opto/machnode.hpp"
37 #include "opto/matcher.hpp"
38 #include "opto/memnode.hpp"
39 #include "opto/mulnode.hpp"
40 #include "opto/narrowptrnode.hpp"
41 #include "opto/phaseX.hpp"
42 #include "opto/regmask.hpp"
43 #include "utilities/copy.hpp"
44
45 // Portions of code courtesy of Clifford Click
46
47 // Optimization - Graph Style
48
49 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
50
51 //=============================================================================
52 uint MemNode::size_of() const { return sizeof(*this); }
53
54 const TypePtr *MemNode::adr_type() const {
55 Node* adr = in(Address);
56 const TypePtr* cross_check = NULL;
57 DEBUG_ONLY(cross_check = _adr_type);
58 return calculate_adr_type(adr->bottom_type(), cross_check);
59 }
60
61 #ifndef PRODUCT
62 void MemNode::dump_spec(outputStream *st) const {
63 if (in(Address) == NULL) return; // node is dead
64 #ifndef ASSERT
65 // fake the missing field
66 const TypePtr* _adr_type = NULL;
67 if (in(Address) != NULL)
68 _adr_type = in(Address)->bottom_type()->isa_ptr();
69 #endif
70 dump_adr_type(this, _adr_type, st);
71
72 Compile* C = Compile::current();
73 if( C->alias_type(_adr_type)->is_volatile() )
74 st->print(" Volatile!");
75 }
76
77 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
78 st->print(" @");
79 if (adr_type == NULL) {
80 st->print("NULL");
81 } else {
82 adr_type->dump_on(st);
83 Compile* C = Compile::current();
84 Compile::AliasType* atp = NULL;
85 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
86 if (atp == NULL)
87 st->print(", idx=?\?;");
88 else if (atp->index() == Compile::AliasIdxBot)
89 st->print(", idx=Bot;");
90 else if (atp->index() == Compile::AliasIdxTop)
91 st->print(", idx=Top;");
92 else if (atp->index() == Compile::AliasIdxRaw)
93 st->print(", idx=Raw;");
94 else {
95 ciField* field = atp->field();
96 if (field) {
97 st->print(", name=");
98 field->print_name_on(st);
99 }
100 st->print(", idx=%d;", atp->index());
101 }
102 }
103 }
104
105 extern void print_alias_types();
106
107 #endif
108
109 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
110 assert((t_oop != NULL), "sanity");
111 bool is_instance = t_oop->is_known_instance_field();
112 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
113 (load != NULL) && load->is_Load() &&
114 (phase->is_IterGVN() != NULL);
115 if (!(is_instance || is_boxed_value_load))
116 return mchain; // don't try to optimize non-instance types
117 uint instance_id = t_oop->instance_id();
118 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
119 Node *prev = NULL;
120 Node *result = mchain;
121 while (prev != result) {
122 prev = result;
123 if (result == start_mem)
124 break; // hit one of our sentinels
125 // skip over a call which does not affect this memory slice
126 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
127 Node *proj_in = result->in(0);
128 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
129 break; // hit one of our sentinels
130 } else if (proj_in->is_Call()) {
131 CallNode *call = proj_in->as_Call();
132 if (!call->may_modify(t_oop, phase)) { // returns false for instances
133 result = call->in(TypeFunc::Memory);
134 }
135 } else if (proj_in->is_Initialize()) {
136 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
137 // Stop if this is the initialization for the object instance which
138 // which contains this memory slice, otherwise skip over it.
139 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
140 break;
141 }
142 if (is_instance) {
143 result = proj_in->in(TypeFunc::Memory);
144 } else if (is_boxed_value_load) {
145 Node* klass = alloc->in(AllocateNode::KlassNode);
146 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
147 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
148 result = proj_in->in(TypeFunc::Memory); // not related allocation
149 }
150 }
151 } else if (proj_in->is_MemBar()) {
152 result = proj_in->in(TypeFunc::Memory);
153 } else {
154 assert(false, "unexpected projection");
155 }
156 } else if (result->is_ClearArray()) {
157 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
158 // Can not bypass initialization of the instance
159 // we are looking for.
160 break;
161 }
162 // Otherwise skip it (the call updated 'result' value).
163 } else if (result->is_MergeMem()) {
164 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
165 }
166 }
167 return result;
168 }
169
170 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
171 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
172 if (t_oop == NULL)
173 return mchain; // don't try to optimize non-oop types
174 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
175 bool is_instance = t_oop->is_known_instance_field();
176 PhaseIterGVN *igvn = phase->is_IterGVN();
177 if (is_instance && igvn != NULL && result->is_Phi()) {
178 PhiNode *mphi = result->as_Phi();
179 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
180 const TypePtr *t = mphi->adr_type();
181 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
182 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
183 t->is_oopptr()->cast_to_exactness(true)
184 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
185 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
186 // clone the Phi with our address type
187 result = mphi->split_out_instance(t_adr, igvn);
188 } else {
189 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
190 }
191 }
192 return result;
193 }
194
195 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
196 uint alias_idx = phase->C->get_alias_index(tp);
197 Node *mem = mmem;
198 #ifdef ASSERT
199 {
200 // Check that current type is consistent with the alias index used during graph construction
201 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
202 bool consistent = adr_check == NULL || adr_check->empty() ||
203 phase->C->must_alias(adr_check, alias_idx );
204 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
205 if( !consistent && adr_check != NULL && !adr_check->empty() &&
206 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
207 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
208 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
209 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
210 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
211 // don't assert if it is dead code.
212 consistent = true;
213 }
214 if( !consistent ) {
215 st->print("alias_idx==%d, adr_check==", alias_idx);
216 if( adr_check == NULL ) {
217 st->print("NULL");
218 } else {
219 adr_check->dump();
220 }
221 st->cr();
222 print_alias_types();
223 assert(consistent, "adr_check must match alias idx");
224 }
225 }
226 #endif
227 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
228 // means an array I have not precisely typed yet. Do not do any
229 // alias stuff with it any time soon.
230 const TypeOopPtr *toop = tp->isa_oopptr();
231 if( tp->base() != Type::AnyPtr &&
232 !(toop &&
233 toop->klass() != NULL &&
234 toop->klass()->is_java_lang_Object() &&
235 toop->offset() == Type::OffsetBot) ) {
236 // compress paths and change unreachable cycles to TOP
237 // If not, we can update the input infinitely along a MergeMem cycle
238 // Equivalent code in PhiNode::Ideal
239 Node* m = phase->transform(mmem);
240 // If transformed to a MergeMem, get the desired slice
241 // Otherwise the returned node represents memory for every slice
242 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
243 // Update input if it is progress over what we have now
244 }
245 return mem;
246 }
247
248 //--------------------------Ideal_common---------------------------------------
249 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
250 // Unhook non-raw memories from complete (macro-expanded) initializations.
251 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
252 // If our control input is a dead region, kill all below the region
253 Node *ctl = in(MemNode::Control);
254 if (ctl && remove_dead_region(phase, can_reshape))
255 return this;
256 ctl = in(MemNode::Control);
257 // Don't bother trying to transform a dead node
258 if (ctl && ctl->is_top()) return NodeSentinel;
259
260 PhaseIterGVN *igvn = phase->is_IterGVN();
261 // Wait if control on the worklist.
262 if (ctl && can_reshape && igvn != NULL) {
263 Node* bol = NULL;
264 Node* cmp = NULL;
265 if (ctl->in(0)->is_If()) {
266 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
267 bol = ctl->in(0)->in(1);
268 if (bol->is_Bool())
269 cmp = ctl->in(0)->in(1)->in(1);
270 }
271 if (igvn->_worklist.member(ctl) ||
272 (bol != NULL && igvn->_worklist.member(bol)) ||
273 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
274 // This control path may be dead.
275 // Delay this memory node transformation until the control is processed.
276 phase->is_IterGVN()->_worklist.push(this);
277 return NodeSentinel; // caller will return NULL
278 }
279 }
280 // Ignore if memory is dead, or self-loop
281 Node *mem = in(MemNode::Memory);
282 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
283 assert(mem != this, "dead loop in MemNode::Ideal");
284
285 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
286 // This memory slice may be dead.
287 // Delay this mem node transformation until the memory is processed.
288 phase->is_IterGVN()->_worklist.push(this);
289 return NodeSentinel; // caller will return NULL
290 }
291
292 Node *address = in(MemNode::Address);
293 const Type *t_adr = phase->type(address);
294 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
295
296 if (can_reshape && igvn != NULL &&
297 (igvn->_worklist.member(address) ||
298 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
299 // The address's base and type may change when the address is processed.
300 // Delay this mem node transformation until the address is processed.
301 phase->is_IterGVN()->_worklist.push(this);
302 return NodeSentinel; // caller will return NULL
303 }
304
305 // Do NOT remove or optimize the next lines: ensure a new alias index
306 // is allocated for an oop pointer type before Escape Analysis.
307 // Note: C++ will not remove it since the call has side effect.
308 if (t_adr->isa_oopptr()) {
309 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
310 }
311
312 Node* base = NULL;
313 if (address->is_AddP()) {
314 base = address->in(AddPNode::Base);
315 }
316 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
317 !t_adr->isa_rawptr()) {
318 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
319 // Skip this node optimization if its address has TOP base.
320 return NodeSentinel; // caller will return NULL
321 }
322
323 // Avoid independent memory operations
324 Node* old_mem = mem;
325
326 // The code which unhooks non-raw memories from complete (macro-expanded)
327 // initializations was removed. After macro-expansion all stores catched
328 // by Initialize node became raw stores and there is no information
329 // which memory slices they modify. So it is unsafe to move any memory
330 // operation above these stores. Also in most cases hooked non-raw memories
331 // were already unhooked by using information from detect_ptr_independence()
332 // and find_previous_store().
333
334 if (mem->is_MergeMem()) {
335 MergeMemNode* mmem = mem->as_MergeMem();
336 const TypePtr *tp = t_adr->is_ptr();
337
338 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
339 }
340
341 if (mem != old_mem) {
342 set_req(MemNode::Memory, mem);
343 if (can_reshape && old_mem->outcnt() == 0) {
344 igvn->_worklist.push(old_mem);
345 }
346 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
347 return this;
348 }
349
350 // let the subclass continue analyzing...
351 return NULL;
352 }
353
354 // Helper function for proving some simple control dominations.
355 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
356 // Already assumes that 'dom' is available at 'sub', and that 'sub'
357 // is not a constant (dominated by the method's StartNode).
358 // Used by MemNode::find_previous_store to prove that the
359 // control input of a memory operation predates (dominates)
360 // an allocation it wants to look past.
361 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
362 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
363 return false; // Conservative answer for dead code
364
365 // Check 'dom'. Skip Proj and CatchProj nodes.
366 dom = dom->find_exact_control(dom);
367 if (dom == NULL || dom->is_top())
368 return false; // Conservative answer for dead code
369
370 if (dom == sub) {
371 // For the case when, for example, 'sub' is Initialize and the original
372 // 'dom' is Proj node of the 'sub'.
373 return false;
374 }
375
376 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
377 return true;
378
379 // 'dom' dominates 'sub' if its control edge and control edges
380 // of all its inputs dominate or equal to sub's control edge.
381
382 // Currently 'sub' is either Allocate, Initialize or Start nodes.
383 // Or Region for the check in LoadNode::Ideal();
384 // 'sub' should have sub->in(0) != NULL.
385 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
386 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
387
388 // Get control edge of 'sub'.
389 Node* orig_sub = sub;
390 sub = sub->find_exact_control(sub->in(0));
391 if (sub == NULL || sub->is_top())
392 return false; // Conservative answer for dead code
393
394 assert(sub->is_CFG(), "expecting control");
395
396 if (sub == dom)
397 return true;
398
399 if (sub->is_Start() || sub->is_Root())
400 return false;
401
402 {
403 // Check all control edges of 'dom'.
404
405 ResourceMark rm;
406 Arena* arena = Thread::current()->resource_area();
407 Node_List nlist(arena);
408 Unique_Node_List dom_list(arena);
409
410 dom_list.push(dom);
411 bool only_dominating_controls = false;
412
413 for (uint next = 0; next < dom_list.size(); next++) {
414 Node* n = dom_list.at(next);
415 if (n == orig_sub)
416 return false; // One of dom's inputs dominated by sub.
417 if (!n->is_CFG() && n->pinned()) {
418 // Check only own control edge for pinned non-control nodes.
419 n = n->find_exact_control(n->in(0));
420 if (n == NULL || n->is_top())
421 return false; // Conservative answer for dead code
422 assert(n->is_CFG(), "expecting control");
423 dom_list.push(n);
424 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
425 only_dominating_controls = true;
426 } else if (n->is_CFG()) {
427 if (n->dominates(sub, nlist))
428 only_dominating_controls = true;
429 else
430 return false;
431 } else {
432 // First, own control edge.
433 Node* m = n->find_exact_control(n->in(0));
434 if (m != NULL) {
435 if (m->is_top())
436 return false; // Conservative answer for dead code
437 dom_list.push(m);
438 }
439 // Now, the rest of edges.
440 uint cnt = n->req();
441 for (uint i = 1; i < cnt; i++) {
442 m = n->find_exact_control(n->in(i));
443 if (m == NULL || m->is_top())
444 continue;
445 dom_list.push(m);
446 }
447 }
448 }
449 return only_dominating_controls;
450 }
451 }
452
453 //---------------------detect_ptr_independence---------------------------------
454 // Used by MemNode::find_previous_store to prove that two base
455 // pointers are never equal.
456 // The pointers are accompanied by their associated allocations,
457 // if any, which have been previously discovered by the caller.
458 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
459 Node* p2, AllocateNode* a2,
460 PhaseTransform* phase) {
461 // Attempt to prove that these two pointers cannot be aliased.
462 // They may both manifestly be allocations, and they should differ.
463 // Or, if they are not both allocations, they can be distinct constants.
464 // Otherwise, one is an allocation and the other a pre-existing value.
465 if (a1 == NULL && a2 == NULL) { // neither an allocation
466 return (p1 != p2) && p1->is_Con() && p2->is_Con();
467 } else if (a1 != NULL && a2 != NULL) { // both allocations
468 return (a1 != a2);
469 } else if (a1 != NULL) { // one allocation a1
470 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
471 return all_controls_dominate(p2, a1);
472 } else { //(a2 != NULL) // one allocation a2
473 return all_controls_dominate(p1, a2);
474 }
475 return false;
476 }
477
478
479 // The logic for reordering loads and stores uses four steps:
480 // (a) Walk carefully past stores and initializations which we
481 // can prove are independent of this load.
482 // (b) Observe that the next memory state makes an exact match
483 // with self (load or store), and locate the relevant store.
484 // (c) Ensure that, if we were to wire self directly to the store,
485 // the optimizer would fold it up somehow.
486 // (d) Do the rewiring, and return, depending on some other part of
487 // the optimizer to fold up the load.
488 // This routine handles steps (a) and (b). Steps (c) and (d) are
489 // specific to loads and stores, so they are handled by the callers.
490 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
491 //
492 Node* MemNode::find_previous_store(PhaseTransform* phase) {
493 Node* ctrl = in(MemNode::Control);
494 Node* adr = in(MemNode::Address);
495 intptr_t offset = 0;
496 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
497 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
498
499 if (offset == Type::OffsetBot)
500 return NULL; // cannot unalias unless there are precise offsets
501
502 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
503
504 intptr_t size_in_bytes = memory_size();
505
506 Node* mem = in(MemNode::Memory); // start searching here...
507
508 int cnt = 50; // Cycle limiter
509 for (;;) { // While we can dance past unrelated stores...
510 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
511
512 if (mem->is_Store()) {
513 Node* st_adr = mem->in(MemNode::Address);
514 intptr_t st_offset = 0;
515 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
516 if (st_base == NULL)
517 break; // inscrutable pointer
518 if (st_offset != offset && st_offset != Type::OffsetBot) {
519 const int MAX_STORE = BytesPerLong;
520 if (st_offset >= offset + size_in_bytes ||
521 st_offset <= offset - MAX_STORE ||
522 st_offset <= offset - mem->as_Store()->memory_size()) {
523 // Success: The offsets are provably independent.
524 // (You may ask, why not just test st_offset != offset and be done?
525 // The answer is that stores of different sizes can co-exist
526 // in the same sequence of RawMem effects. We sometimes initialize
527 // a whole 'tile' of array elements with a single jint or jlong.)
528 mem = mem->in(MemNode::Memory);
529 continue; // (a) advance through independent store memory
530 }
531 }
532 if (st_base != base &&
533 detect_ptr_independence(base, alloc,
534 st_base,
535 AllocateNode::Ideal_allocation(st_base, phase),
536 phase)) {
537 // Success: The bases are provably independent.
538 mem = mem->in(MemNode::Memory);
539 continue; // (a) advance through independent store memory
540 }
541
542 // (b) At this point, if the bases or offsets do not agree, we lose,
543 // since we have not managed to prove 'this' and 'mem' independent.
544 if (st_base == base && st_offset == offset) {
545 return mem; // let caller handle steps (c), (d)
546 }
547
548 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
549 InitializeNode* st_init = mem->in(0)->as_Initialize();
550 AllocateNode* st_alloc = st_init->allocation();
551 if (st_alloc == NULL)
552 break; // something degenerated
553 bool known_identical = false;
554 bool known_independent = false;
555 if (alloc == st_alloc)
556 known_identical = true;
557 else if (alloc != NULL)
558 known_independent = true;
559 else if (all_controls_dominate(this, st_alloc))
560 known_independent = true;
561
562 if (known_independent) {
563 // The bases are provably independent: Either they are
564 // manifestly distinct allocations, or else the control
565 // of this load dominates the store's allocation.
566 int alias_idx = phase->C->get_alias_index(adr_type());
567 if (alias_idx == Compile::AliasIdxRaw) {
568 mem = st_alloc->in(TypeFunc::Memory);
569 } else {
570 mem = st_init->memory(alias_idx);
571 }
572 continue; // (a) advance through independent store memory
573 }
574
575 // (b) at this point, if we are not looking at a store initializing
576 // the same allocation we are loading from, we lose.
577 if (known_identical) {
578 // From caller, can_see_stored_value will consult find_captured_store.
579 return mem; // let caller handle steps (c), (d)
580 }
581
582 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
583 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
584 if (mem->is_Proj() && mem->in(0)->is_Call()) {
585 CallNode *call = mem->in(0)->as_Call();
586 if (!call->may_modify(addr_t, phase)) {
587 mem = call->in(TypeFunc::Memory);
588 continue; // (a) advance through independent call memory
589 }
590 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
591 mem = mem->in(0)->in(TypeFunc::Memory);
592 continue; // (a) advance through independent MemBar memory
593 } else if (mem->is_ClearArray()) {
594 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
595 // (the call updated 'mem' value)
596 continue; // (a) advance through independent allocation memory
597 } else {
598 // Can not bypass initialization of the instance
599 // we are looking for.
600 return mem;
601 }
602 } else if (mem->is_MergeMem()) {
603 int alias_idx = phase->C->get_alias_index(adr_type());
604 mem = mem->as_MergeMem()->memory_at(alias_idx);
605 continue; // (a) advance through independent MergeMem memory
606 }
607 }
608
609 // Unless there is an explicit 'continue', we must bail out here,
610 // because 'mem' is an inscrutable memory state (e.g., a call).
611 break;
612 }
613
614 return NULL; // bail out
615 }
616
617 //----------------------calculate_adr_type-------------------------------------
618 // Helper function. Notices when the given type of address hits top or bottom.
619 // Also, asserts a cross-check of the type against the expected address type.
620 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
621 if (t == Type::TOP) return NULL; // does not touch memory any more?
622 #ifdef PRODUCT
623 cross_check = NULL;
624 #else
625 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
626 #endif
627 const TypePtr* tp = t->isa_ptr();
628 if (tp == NULL) {
629 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
630 return TypePtr::BOTTOM; // touches lots of memory
631 } else {
632 #ifdef ASSERT
633 // %%%% [phh] We don't check the alias index if cross_check is
634 // TypeRawPtr::BOTTOM. Needs to be investigated.
635 if (cross_check != NULL &&
636 cross_check != TypePtr::BOTTOM &&
637 cross_check != TypeRawPtr::BOTTOM) {
638 // Recheck the alias index, to see if it has changed (due to a bug).
639 Compile* C = Compile::current();
640 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
641 "must stay in the original alias category");
642 // The type of the address must be contained in the adr_type,
643 // disregarding "null"-ness.
644 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
645 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
646 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
647 "real address must not escape from expected memory type");
648 }
649 #endif
650 return tp;
651 }
652 }
653
654 //------------------------adr_phi_is_loop_invariant----------------------------
655 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
656 // loop is loop invariant. Make a quick traversal of Phi and associated
657 // CastPP nodes, looking to see if they are a closed group within the loop.
658 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
659 // The idea is that the phi-nest must boil down to only CastPP nodes
660 // with the same data. This implies that any path into the loop already
661 // includes such a CastPP, and so the original cast, whatever its input,
662 // must be covered by an equivalent cast, with an earlier control input.
663 ResourceMark rm;
664
665 // The loop entry input of the phi should be the unique dominating
666 // node for every Phi/CastPP in the loop.
667 Unique_Node_List closure;
668 closure.push(adr_phi->in(LoopNode::EntryControl));
669
670 // Add the phi node and the cast to the worklist.
671 Unique_Node_List worklist;
672 worklist.push(adr_phi);
673 if( cast != NULL ){
674 if( !cast->is_ConstraintCast() ) return false;
675 worklist.push(cast);
676 }
677
678 // Begin recursive walk of phi nodes.
679 while( worklist.size() ){
680 // Take a node off the worklist
681 Node *n = worklist.pop();
682 if( !closure.member(n) ){
683 // Add it to the closure.
684 closure.push(n);
685 // Make a sanity check to ensure we don't waste too much time here.
686 if( closure.size() > 20) return false;
687 // This node is OK if:
688 // - it is a cast of an identical value
689 // - or it is a phi node (then we add its inputs to the worklist)
690 // Otherwise, the node is not OK, and we presume the cast is not invariant
691 if( n->is_ConstraintCast() ){
692 worklist.push(n->in(1));
693 } else if( n->is_Phi() ) {
694 for( uint i = 1; i < n->req(); i++ ) {
695 worklist.push(n->in(i));
696 }
697 } else {
698 return false;
699 }
700 }
701 }
702
703 // Quit when the worklist is empty, and we've found no offending nodes.
704 return true;
705 }
706
707 //------------------------------Ideal_DU_postCCP-------------------------------
708 // Find any cast-away of null-ness and keep its control. Null cast-aways are
709 // going away in this pass and we need to make this memory op depend on the
710 // gating null check.
711 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
712 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
713 }
714
715 // I tried to leave the CastPP's in. This makes the graph more accurate in
716 // some sense; we get to keep around the knowledge that an oop is not-null
717 // after some test. Alas, the CastPP's interfere with GVN (some values are
718 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
719 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
720 // some of the more trivial cases in the optimizer. Removing more useless
721 // Phi's started allowing Loads to illegally float above null checks. I gave
722 // up on this approach. CNC 10/20/2000
723 // This static method may be called not from MemNode (EncodePNode calls it).
724 // Only the control edge of the node 'n' might be updated.
725 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
726 Node *skipped_cast = NULL;
727 // Need a null check? Regular static accesses do not because they are
728 // from constant addresses. Array ops are gated by the range check (which
729 // always includes a NULL check). Just check field ops.
730 if( n->in(MemNode::Control) == NULL ) {
731 // Scan upwards for the highest location we can place this memory op.
732 while( true ) {
733 switch( adr->Opcode() ) {
734
735 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
736 adr = adr->in(AddPNode::Base);
737 continue;
738
739 case Op_DecodeN: // No change to NULL-ness, so peek thru
740 case Op_DecodeNKlass:
741 adr = adr->in(1);
742 continue;
743
744 case Op_EncodeP:
745 case Op_EncodePKlass:
746 // EncodeP node's control edge could be set by this method
747 // when EncodeP node depends on CastPP node.
748 //
749 // Use its control edge for memory op because EncodeP may go away
750 // later when it is folded with following or preceding DecodeN node.
751 if (adr->in(0) == NULL) {
752 // Keep looking for cast nodes.
753 adr = adr->in(1);
754 continue;
755 }
756 ccp->hash_delete(n);
757 n->set_req(MemNode::Control, adr->in(0));
758 ccp->hash_insert(n);
759 return n;
760
761 case Op_CastPP:
762 // If the CastPP is useless, just peek on through it.
763 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
764 // Remember the cast that we've peeked though. If we peek
765 // through more than one, then we end up remembering the highest
766 // one, that is, if in a loop, the one closest to the top.
767 skipped_cast = adr;
768 adr = adr->in(1);
769 continue;
770 }
771 // CastPP is going away in this pass! We need this memory op to be
772 // control-dependent on the test that is guarding the CastPP.
773 ccp->hash_delete(n);
774 n->set_req(MemNode::Control, adr->in(0));
775 ccp->hash_insert(n);
776 return n;
777
778 case Op_Phi:
779 // Attempt to float above a Phi to some dominating point.
780 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
781 // If we've already peeked through a Cast (which could have set the
782 // control), we can't float above a Phi, because the skipped Cast
783 // may not be loop invariant.
784 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
785 adr = adr->in(1);
786 continue;
787 }
788 }
789
790 // Intentional fallthrough!
791
792 // No obvious dominating point. The mem op is pinned below the Phi
793 // by the Phi itself. If the Phi goes away (no true value is merged)
794 // then the mem op can float, but not indefinitely. It must be pinned
795 // behind the controls leading to the Phi.
796 case Op_CheckCastPP:
797 // These usually stick around to change address type, however a
798 // useless one can be elided and we still need to pick up a control edge
799 if (adr->in(0) == NULL) {
800 // This CheckCastPP node has NO control and is likely useless. But we
801 // need check further up the ancestor chain for a control input to keep
802 // the node in place. 4959717.
803 skipped_cast = adr;
804 adr = adr->in(1);
805 continue;
806 }
807 ccp->hash_delete(n);
808 n->set_req(MemNode::Control, adr->in(0));
809 ccp->hash_insert(n);
810 return n;
811
812 // List of "safe" opcodes; those that implicitly block the memory
813 // op below any null check.
814 case Op_CastX2P: // no null checks on native pointers
815 case Op_Parm: // 'this' pointer is not null
816 case Op_LoadP: // Loading from within a klass
817 case Op_LoadN: // Loading from within a klass
818 case Op_LoadKlass: // Loading from within a klass
819 case Op_LoadNKlass: // Loading from within a klass
820 case Op_ConP: // Loading from a klass
821 case Op_ConN: // Loading from a klass
822 case Op_ConNKlass: // Loading from a klass
823 case Op_CreateEx: // Sucking up the guts of an exception oop
824 case Op_Con: // Reading from TLS
825 case Op_CMoveP: // CMoveP is pinned
826 case Op_CMoveN: // CMoveN is pinned
827 break; // No progress
828
829 case Op_Proj: // Direct call to an allocation routine
830 case Op_SCMemProj: // Memory state from store conditional ops
831 #ifdef ASSERT
832 {
833 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
834 const Node* call = adr->in(0);
835 if (call->is_CallJava()) {
836 const CallJavaNode* call_java = call->as_CallJava();
837 const TypeTuple *r = call_java->tf()->range();
838 assert(r->cnt() > TypeFunc::Parms, "must return value");
839 const Type* ret_type = r->field_at(TypeFunc::Parms);
840 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
841 // We further presume that this is one of
842 // new_instance_Java, new_array_Java, or
843 // the like, but do not assert for this.
844 } else if (call->is_Allocate()) {
845 // similar case to new_instance_Java, etc.
846 } else if (!call->is_CallLeaf()) {
847 // Projections from fetch_oop (OSR) are allowed as well.
848 ShouldNotReachHere();
849 }
850 }
851 #endif
852 break;
853 default:
854 ShouldNotReachHere();
855 }
856 break;
857 }
858 }
859
860 return NULL; // No progress
861 }
862
863
864 //=============================================================================
865 uint LoadNode::size_of() const { return sizeof(*this); }
866 uint LoadNode::cmp( const Node &n ) const
867 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
868 const Type *LoadNode::bottom_type() const { return _type; }
869 uint LoadNode::ideal_reg() const {
870 return _type->ideal_reg();
871 }
872
873 #ifndef PRODUCT
874 void LoadNode::dump_spec(outputStream *st) const {
875 MemNode::dump_spec(st);
876 if( !Verbose && !WizardMode ) {
877 // standard dump does this in Verbose and WizardMode
878 st->print(" #"); _type->dump_on(st);
879 }
880 }
881 #endif
882
883 #ifdef ASSERT
884 //----------------------------is_immutable_value-------------------------------
885 // Helper function to allow a raw load without control edge for some cases
886 bool LoadNode::is_immutable_value(Node* adr) {
887 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
888 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
889 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
890 in_bytes(JavaThread::osthread_offset())));
891 }
892 #endif
893
894 //----------------------------LoadNode::make-----------------------------------
895 // Polymorphic factory method:
896 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo) {
897 Compile* C = gvn.C;
898
899 // sanity check the alias category against the created node type
900 assert(!(adr_type->isa_oopptr() &&
901 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
902 "use LoadKlassNode instead");
903 assert(!(adr_type->isa_aryptr() &&
904 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
905 "use LoadRangeNode instead");
906 // Check control edge of raw loads
907 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
908 // oop will be recorded in oop map if load crosses safepoint
909 rt->isa_oopptr() || is_immutable_value(adr),
910 "raw memory operations should have control edge");
911 switch (bt) {
912 case T_BOOLEAN: return new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo);
913 case T_BYTE: return new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo);
914 case T_INT: return new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo);
915 case T_CHAR: return new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo);
916 case T_SHORT: return new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo);
917 case T_LONG: return new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo);
918 case T_FLOAT: return new LoadFNode (ctl, mem, adr, adr_type, rt, mo);
919 case T_DOUBLE: return new LoadDNode (ctl, mem, adr, adr_type, rt, mo);
920 case T_ADDRESS: return new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo);
921 case T_OBJECT:
922 #ifdef _LP64
923 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
924 Node* load = gvn.transform(new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo));
925 return new DecodeNNode(load, load->bottom_type()->make_ptr());
926 } else
927 #endif
928 {
929 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
930 return new LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo);
931 }
932 }
933 ShouldNotReachHere();
934 return (LoadNode*)NULL;
935 }
936
937 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo) {
938 bool require_atomic = true;
939 return new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, require_atomic);
940 }
941
942 LoadDNode* LoadDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo) {
943 bool require_atomic = true;
944 return new LoadDNode(ctl, mem, adr, adr_type, rt, mo, require_atomic);
945 }
946
947
948
949 //------------------------------hash-------------------------------------------
950 uint LoadNode::hash() const {
951 // unroll addition of interesting fields
952 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
953 }
954
955 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
956 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
957 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
958 bool is_stable_ary = FoldStableValues &&
959 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
960 tp->isa_aryptr()->is_stable();
961
962 return (eliminate_boxing && non_volatile) || is_stable_ary;
963 }
964
965 return false;
966 }
967
968 //---------------------------can_see_stored_value------------------------------
969 // This routine exists to make sure this set of tests is done the same
970 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
971 // will change the graph shape in a way which makes memory alive twice at the
972 // same time (uses the Oracle model of aliasing), then some
973 // LoadXNode::Identity will fold things back to the equivalence-class model
974 // of aliasing.
975 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
976 Node* ld_adr = in(MemNode::Address);
977 intptr_t ld_off = 0;
978 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
979 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
980 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
981 // This is more general than load from boxing objects.
982 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
983 uint alias_idx = atp->index();
984 bool final = !atp->is_rewritable();
985 Node* result = NULL;
986 Node* current = st;
987 // Skip through chains of MemBarNodes checking the MergeMems for
988 // new states for the slice of this load. Stop once any other
989 // kind of node is encountered. Loads from final memory can skip
990 // through any kind of MemBar but normal loads shouldn't skip
991 // through MemBarAcquire since the could allow them to move out of
992 // a synchronized region.
993 while (current->is_Proj()) {
994 int opc = current->in(0)->Opcode();
995 if ((final && (opc == Op_MemBarAcquire ||
996 opc == Op_MemBarAcquireLock ||
997 opc == Op_LoadFence)) ||
998 opc == Op_MemBarRelease ||
999 opc == Op_StoreFence ||
1000 opc == Op_MemBarReleaseLock ||
1001 opc == Op_MemBarCPUOrder) {
1002 Node* mem = current->in(0)->in(TypeFunc::Memory);
1003 if (mem->is_MergeMem()) {
1004 MergeMemNode* merge = mem->as_MergeMem();
1005 Node* new_st = merge->memory_at(alias_idx);
1006 if (new_st == merge->base_memory()) {
1007 // Keep searching
1008 current = new_st;
1009 continue;
1010 }
1011 // Save the new memory state for the slice and fall through
1012 // to exit.
1013 result = new_st;
1014 }
1015 }
1016 break;
1017 }
1018 if (result != NULL) {
1019 st = result;
1020 }
1021 }
1022
1023 // Loop around twice in the case Load -> Initialize -> Store.
1024 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1025 for (int trip = 0; trip <= 1; trip++) {
1026
1027 if (st->is_Store()) {
1028 Node* st_adr = st->in(MemNode::Address);
1029 if (!phase->eqv(st_adr, ld_adr)) {
1030 // Try harder before giving up... Match raw and non-raw pointers.
1031 intptr_t st_off = 0;
1032 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1033 if (alloc == NULL) return NULL;
1034 if (alloc != ld_alloc) return NULL;
1035 if (ld_off != st_off) return NULL;
1036 // At this point we have proven something like this setup:
1037 // A = Allocate(...)
1038 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1039 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1040 // (Actually, we haven't yet proven the Q's are the same.)
1041 // In other words, we are loading from a casted version of
1042 // the same pointer-and-offset that we stored to.
1043 // Thus, we are able to replace L by V.
1044 }
1045 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1046 if (store_Opcode() != st->Opcode())
1047 return NULL;
1048 return st->in(MemNode::ValueIn);
1049 }
1050
1051 // A load from a freshly-created object always returns zero.
1052 // (This can happen after LoadNode::Ideal resets the load's memory input
1053 // to find_captured_store, which returned InitializeNode::zero_memory.)
1054 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1055 (st->in(0) == ld_alloc) &&
1056 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1057 // return a zero value for the load's basic type
1058 // (This is one of the few places where a generic PhaseTransform
1059 // can create new nodes. Think of it as lazily manifesting
1060 // virtually pre-existing constants.)
1061 return phase->zerocon(memory_type());
1062 }
1063
1064 // A load from an initialization barrier can match a captured store.
1065 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1066 InitializeNode* init = st->in(0)->as_Initialize();
1067 AllocateNode* alloc = init->allocation();
1068 if ((alloc != NULL) && (alloc == ld_alloc)) {
1069 // examine a captured store value
1070 st = init->find_captured_store(ld_off, memory_size(), phase);
1071 if (st != NULL)
1072 continue; // take one more trip around
1073 }
1074 }
1075
1076 // Load boxed value from result of valueOf() call is input parameter.
1077 if (this->is_Load() && ld_adr->is_AddP() &&
1078 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1079 intptr_t ignore = 0;
1080 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1081 if (base != NULL && base->is_Proj() &&
1082 base->as_Proj()->_con == TypeFunc::Parms &&
1083 base->in(0)->is_CallStaticJava() &&
1084 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1085 return base->in(0)->in(TypeFunc::Parms);
1086 }
1087 }
1088
1089 break;
1090 }
1091
1092 return NULL;
1093 }
1094
1095 //----------------------is_instance_field_load_with_local_phi------------------
1096 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1097 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1098 in(Address)->is_AddP() ) {
1099 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1100 // Only instances and boxed values.
1101 if( t_oop != NULL &&
1102 (t_oop->is_ptr_to_boxed_value() ||
1103 t_oop->is_known_instance_field()) &&
1104 t_oop->offset() != Type::OffsetBot &&
1105 t_oop->offset() != Type::OffsetTop) {
1106 return true;
1107 }
1108 }
1109 return false;
1110 }
1111
1112 //------------------------------Identity---------------------------------------
1113 // Loads are identity if previous store is to same address
1114 Node *LoadNode::Identity( PhaseTransform *phase ) {
1115 // If the previous store-maker is the right kind of Store, and the store is
1116 // to the same address, then we are equal to the value stored.
1117 Node* mem = in(Memory);
1118 Node* value = can_see_stored_value(mem, phase);
1119 if( value ) {
1120 // byte, short & char stores truncate naturally.
1121 // A load has to load the truncated value which requires
1122 // some sort of masking operation and that requires an
1123 // Ideal call instead of an Identity call.
1124 if (memory_size() < BytesPerInt) {
1125 // If the input to the store does not fit with the load's result type,
1126 // it must be truncated via an Ideal call.
1127 if (!phase->type(value)->higher_equal(phase->type(this)))
1128 return this;
1129 }
1130 // (This works even when value is a Con, but LoadNode::Value
1131 // usually runs first, producing the singleton type of the Con.)
1132 return value;
1133 }
1134
1135 // Search for an existing data phi which was generated before for the same
1136 // instance's field to avoid infinite generation of phis in a loop.
1137 Node *region = mem->in(0);
1138 if (is_instance_field_load_with_local_phi(region)) {
1139 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1140 int this_index = phase->C->get_alias_index(addr_t);
1141 int this_offset = addr_t->offset();
1142 int this_iid = addr_t->instance_id();
1143 if (!addr_t->is_known_instance() &&
1144 addr_t->is_ptr_to_boxed_value()) {
1145 // Use _idx of address base (could be Phi node) for boxed values.
1146 intptr_t ignore = 0;
1147 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1148 this_iid = base->_idx;
1149 }
1150 const Type* this_type = bottom_type();
1151 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1152 Node* phi = region->fast_out(i);
1153 if (phi->is_Phi() && phi != mem &&
1154 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) {
1155 return phi;
1156 }
1157 }
1158 }
1159
1160 return this;
1161 }
1162
1163 // We're loading from an object which has autobox behaviour.
1164 // If this object is result of a valueOf call we'll have a phi
1165 // merging a newly allocated object and a load from the cache.
1166 // We want to replace this load with the original incoming
1167 // argument to the valueOf call.
1168 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1169 assert(phase->C->eliminate_boxing(), "sanity");
1170 intptr_t ignore = 0;
1171 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1172 if ((base == NULL) || base->is_Phi()) {
1173 // Push the loads from the phi that comes from valueOf up
1174 // through it to allow elimination of the loads and the recovery
1175 // of the original value. It is done in split_through_phi().
1176 return NULL;
1177 } else if (base->is_Load() ||
1178 base->is_DecodeN() && base->in(1)->is_Load()) {
1179 // Eliminate the load of boxed value for integer types from the cache
1180 // array by deriving the value from the index into the array.
1181 // Capture the offset of the load and then reverse the computation.
1182
1183 // Get LoadN node which loads a boxing object from 'cache' array.
1184 if (base->is_DecodeN()) {
1185 base = base->in(1);
1186 }
1187 if (!base->in(Address)->is_AddP()) {
1188 return NULL; // Complex address
1189 }
1190 AddPNode* address = base->in(Address)->as_AddP();
1191 Node* cache_base = address->in(AddPNode::Base);
1192 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1193 // Get ConP node which is static 'cache' field.
1194 cache_base = cache_base->in(1);
1195 }
1196 if ((cache_base != NULL) && cache_base->is_Con()) {
1197 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1198 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1199 Node* elements[4];
1200 int shift = exact_log2(type2aelembytes(T_OBJECT));
1201 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1202 if ((count > 0) && elements[0]->is_Con() &&
1203 ((count == 1) ||
1204 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1205 elements[1]->in(2) == phase->intcon(shift))) {
1206 ciObjArray* array = base_type->const_oop()->as_obj_array();
1207 // Fetch the box object cache[0] at the base of the array and get its value
1208 ciInstance* box = array->obj_at(0)->as_instance();
1209 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1210 assert(ik->is_box_klass(), "sanity");
1211 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1212 if (ik->nof_nonstatic_fields() == 1) {
1213 // This should be true nonstatic_field_at requires calling
1214 // nof_nonstatic_fields so check it anyway
1215 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1216 BasicType bt = c.basic_type();
1217 // Only integer types have boxing cache.
1218 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1219 bt == T_BYTE || bt == T_SHORT ||
1220 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1221 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1222 if (cache_low != (int)cache_low) {
1223 return NULL; // should not happen since cache is array indexed by value
1224 }
1225 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1226 if (offset != (int)offset) {
1227 return NULL; // should not happen since cache is array indexed by value
1228 }
1229 // Add up all the offsets making of the address of the load
1230 Node* result = elements[0];
1231 for (int i = 1; i < count; i++) {
1232 result = phase->transform(new AddXNode(result, elements[i]));
1233 }
1234 // Remove the constant offset from the address and then
1235 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1236 // remove the scaling of the offset to recover the original index.
1237 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1238 // Peel the shift off directly but wrap it in a dummy node
1239 // since Ideal can't return existing nodes
1240 result = new RShiftXNode(result->in(1), phase->intcon(0));
1241 } else if (result->is_Add() && result->in(2)->is_Con() &&
1242 result->in(1)->Opcode() == Op_LShiftX &&
1243 result->in(1)->in(2) == phase->intcon(shift)) {
1244 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1245 // but for boxing cache access we know that X<<Z will not overflow
1246 // (there is range check) so we do this optimizatrion by hand here.
1247 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1248 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1249 } else {
1250 result = new RShiftXNode(result, phase->intcon(shift));
1251 }
1252 #ifdef _LP64
1253 if (bt != T_LONG) {
1254 result = new ConvL2INode(phase->transform(result));
1255 }
1256 #else
1257 if (bt == T_LONG) {
1258 result = new ConvI2LNode(phase->transform(result));
1259 }
1260 #endif
1261 return result;
1262 }
1263 }
1264 }
1265 }
1266 }
1267 return NULL;
1268 }
1269
1270 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1271 Node* region = phi->in(0);
1272 if (region == NULL) {
1273 return false; // Wait stable graph
1274 }
1275 uint cnt = phi->req();
1276 for (uint i = 1; i < cnt; i++) {
1277 Node* rc = region->in(i);
1278 if (rc == NULL || phase->type(rc) == Type::TOP)
1279 return false; // Wait stable graph
1280 Node* in = phi->in(i);
1281 if (in == NULL || phase->type(in) == Type::TOP)
1282 return false; // Wait stable graph
1283 }
1284 return true;
1285 }
1286 //------------------------------split_through_phi------------------------------
1287 // Split instance or boxed field load through Phi.
1288 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1289 Node* mem = in(Memory);
1290 Node* address = in(Address);
1291 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1292
1293 assert((t_oop != NULL) &&
1294 (t_oop->is_known_instance_field() ||
1295 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1296
1297 Compile* C = phase->C;
1298 intptr_t ignore = 0;
1299 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1300 bool base_is_phi = (base != NULL) && base->is_Phi();
1301 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1302 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1303 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1304
1305 if (!((mem->is_Phi() || base_is_phi) &&
1306 (load_boxed_values || t_oop->is_known_instance_field()))) {
1307 return NULL; // memory is not Phi
1308 }
1309
1310 if (mem->is_Phi()) {
1311 if (!stable_phi(mem->as_Phi(), phase)) {
1312 return NULL; // Wait stable graph
1313 }
1314 uint cnt = mem->req();
1315 // Check for loop invariant memory.
1316 if (cnt == 3) {
1317 for (uint i = 1; i < cnt; i++) {
1318 Node* in = mem->in(i);
1319 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1320 if (m == mem) {
1321 set_req(Memory, mem->in(cnt - i));
1322 return this; // made change
1323 }
1324 }
1325 }
1326 }
1327 if (base_is_phi) {
1328 if (!stable_phi(base->as_Phi(), phase)) {
1329 return NULL; // Wait stable graph
1330 }
1331 uint cnt = base->req();
1332 // Check for loop invariant memory.
1333 if (cnt == 3) {
1334 for (uint i = 1; i < cnt; i++) {
1335 if (base->in(i) == base) {
1336 return NULL; // Wait stable graph
1337 }
1338 }
1339 }
1340 }
1341
1342 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1343
1344 // Split through Phi (see original code in loopopts.cpp).
1345 assert(C->have_alias_type(t_oop), "instance should have alias type");
1346
1347 // Do nothing here if Identity will find a value
1348 // (to avoid infinite chain of value phis generation).
1349 if (!phase->eqv(this, this->Identity(phase)))
1350 return NULL;
1351
1352 // Select Region to split through.
1353 Node* region;
1354 if (!base_is_phi) {
1355 assert(mem->is_Phi(), "sanity");
1356 region = mem->in(0);
1357 // Skip if the region dominates some control edge of the address.
1358 if (!MemNode::all_controls_dominate(address, region))
1359 return NULL;
1360 } else if (!mem->is_Phi()) {
1361 assert(base_is_phi, "sanity");
1362 region = base->in(0);
1363 // Skip if the region dominates some control edge of the memory.
1364 if (!MemNode::all_controls_dominate(mem, region))
1365 return NULL;
1366 } else if (base->in(0) != mem->in(0)) {
1367 assert(base_is_phi && mem->is_Phi(), "sanity");
1368 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1369 region = base->in(0);
1370 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1371 region = mem->in(0);
1372 } else {
1373 return NULL; // complex graph
1374 }
1375 } else {
1376 assert(base->in(0) == mem->in(0), "sanity");
1377 region = mem->in(0);
1378 }
1379
1380 const Type* this_type = this->bottom_type();
1381 int this_index = C->get_alias_index(t_oop);
1382 int this_offset = t_oop->offset();
1383 int this_iid = t_oop->instance_id();
1384 if (!t_oop->is_known_instance() && load_boxed_values) {
1385 // Use _idx of address base for boxed values.
1386 this_iid = base->_idx;
1387 }
1388 PhaseIterGVN* igvn = phase->is_IterGVN();
1389 Node* phi = new PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1390 for (uint i = 1; i < region->req(); i++) {
1391 Node* x;
1392 Node* the_clone = NULL;
1393 if (region->in(i) == C->top()) {
1394 x = C->top(); // Dead path? Use a dead data op
1395 } else {
1396 x = this->clone(); // Else clone up the data op
1397 the_clone = x; // Remember for possible deletion.
1398 // Alter data node to use pre-phi inputs
1399 if (this->in(0) == region) {
1400 x->set_req(0, region->in(i));
1401 } else {
1402 x->set_req(0, NULL);
1403 }
1404 if (mem->is_Phi() && (mem->in(0) == region)) {
1405 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1406 }
1407 if (address->is_Phi() && address->in(0) == region) {
1408 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1409 }
1410 if (base_is_phi && (base->in(0) == region)) {
1411 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1412 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1413 x->set_req(Address, adr_x);
1414 }
1415 }
1416 // Check for a 'win' on some paths
1417 const Type *t = x->Value(igvn);
1418
1419 bool singleton = t->singleton();
1420
1421 // See comments in PhaseIdealLoop::split_thru_phi().
1422 if (singleton && t == Type::TOP) {
1423 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1424 }
1425
1426 if (singleton) {
1427 x = igvn->makecon(t);
1428 } else {
1429 // We now call Identity to try to simplify the cloned node.
1430 // Note that some Identity methods call phase->type(this).
1431 // Make sure that the type array is big enough for
1432 // our new node, even though we may throw the node away.
1433 // (This tweaking with igvn only works because x is a new node.)
1434 igvn->set_type(x, t);
1435 // If x is a TypeNode, capture any more-precise type permanently into Node
1436 // otherwise it will be not updated during igvn->transform since
1437 // igvn->type(x) is set to x->Value() already.
1438 x->raise_bottom_type(t);
1439 Node *y = x->Identity(igvn);
1440 if (y != x) {
1441 x = y;
1442 } else {
1443 y = igvn->hash_find_insert(x);
1444 if (y) {
1445 x = y;
1446 } else {
1447 // Else x is a new node we are keeping
1448 // We do not need register_new_node_with_optimizer
1449 // because set_type has already been called.
1450 igvn->_worklist.push(x);
1451 }
1452 }
1453 }
1454 if (x != the_clone && the_clone != NULL) {
1455 igvn->remove_dead_node(the_clone);
1456 }
1457 phi->set_req(i, x);
1458 }
1459 // Record Phi
1460 igvn->register_new_node_with_optimizer(phi);
1461 return phi;
1462 }
1463
1464 //------------------------------Ideal------------------------------------------
1465 // If the load is from Field memory and the pointer is non-null, we can
1466 // zero out the control input.
1467 // If the offset is constant and the base is an object allocation,
1468 // try to hook me up to the exact initializing store.
1469 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1470 Node* p = MemNode::Ideal_common(phase, can_reshape);
1471 if (p) return (p == NodeSentinel) ? NULL : p;
1472
1473 Node* ctrl = in(MemNode::Control);
1474 Node* address = in(MemNode::Address);
1475
1476 // Skip up past a SafePoint control. Cannot do this for Stores because
1477 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1478 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1479 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1480 ctrl = ctrl->in(0);
1481 set_req(MemNode::Control,ctrl);
1482 }
1483
1484 intptr_t ignore = 0;
1485 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1486 if (base != NULL
1487 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1488 // Check for useless control edge in some common special cases
1489 if (in(MemNode::Control) != NULL
1490 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1491 && all_controls_dominate(base, phase->C->start())) {
1492 // A method-invariant, non-null address (constant or 'this' argument).
1493 set_req(MemNode::Control, NULL);
1494 }
1495 }
1496
1497 Node* mem = in(MemNode::Memory);
1498 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1499
1500 if (can_reshape && (addr_t != NULL)) {
1501 // try to optimize our memory input
1502 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1503 if (opt_mem != mem) {
1504 set_req(MemNode::Memory, opt_mem);
1505 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1506 return this;
1507 }
1508 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1509 if ((t_oop != NULL) &&
1510 (t_oop->is_known_instance_field() ||
1511 t_oop->is_ptr_to_boxed_value())) {
1512 PhaseIterGVN *igvn = phase->is_IterGVN();
1513 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1514 // Delay this transformation until memory Phi is processed.
1515 phase->is_IterGVN()->_worklist.push(this);
1516 return NULL;
1517 }
1518 // Split instance field load through Phi.
1519 Node* result = split_through_phi(phase);
1520 if (result != NULL) return result;
1521
1522 if (t_oop->is_ptr_to_boxed_value()) {
1523 Node* result = eliminate_autobox(phase);
1524 if (result != NULL) return result;
1525 }
1526 }
1527 }
1528
1529 // Check for prior store with a different base or offset; make Load
1530 // independent. Skip through any number of them. Bail out if the stores
1531 // are in an endless dead cycle and report no progress. This is a key
1532 // transform for Reflection. However, if after skipping through the Stores
1533 // we can't then fold up against a prior store do NOT do the transform as
1534 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1535 // array memory alive twice: once for the hoisted Load and again after the
1536 // bypassed Store. This situation only works if EVERYBODY who does
1537 // anti-dependence work knows how to bypass. I.e. we need all
1538 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1539 // the alias index stuff. So instead, peek through Stores and IFF we can
1540 // fold up, do so.
1541 Node* prev_mem = find_previous_store(phase);
1542 // Steps (a), (b): Walk past independent stores to find an exact match.
1543 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1544 // (c) See if we can fold up on the spot, but don't fold up here.
1545 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1546 // just return a prior value, which is done by Identity calls.
1547 if (can_see_stored_value(prev_mem, phase)) {
1548 // Make ready for step (d):
1549 set_req(MemNode::Memory, prev_mem);
1550 return this;
1551 }
1552 }
1553
1554 return NULL; // No further progress
1555 }
1556
1557 // Helper to recognize certain Klass fields which are invariant across
1558 // some group of array types (e.g., int[] or all T[] where T < Object).
1559 const Type*
1560 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1561 ciKlass* klass) const {
1562 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1563 // The field is Klass::_modifier_flags. Return its (constant) value.
1564 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1565 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1566 return TypeInt::make(klass->modifier_flags());
1567 }
1568 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1569 // The field is Klass::_access_flags. Return its (constant) value.
1570 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1571 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1572 return TypeInt::make(klass->access_flags());
1573 }
1574 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1575 // The field is Klass::_layout_helper. Return its constant value if known.
1576 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1577 return TypeInt::make(klass->layout_helper());
1578 }
1579
1580 // No match.
1581 return NULL;
1582 }
1583
1584 // Try to constant-fold a stable array element.
1585 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1586 assert(ary->const_oop(), "array should be constant");
1587 assert(ary->is_stable(), "array should be stable");
1588
1589 // Decode the results of GraphKit::array_element_address.
1590 ciArray* aobj = ary->const_oop()->as_array();
1591 ciConstant con = aobj->element_value_by_offset(off);
1592
1593 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1594 const Type* con_type = Type::make_from_constant(con);
1595 if (con_type != NULL) {
1596 if (con_type->isa_aryptr()) {
1597 // Join with the array element type, in case it is also stable.
1598 int dim = ary->stable_dimension();
1599 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1600 }
1601 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1602 con_type = con_type->make_narrowoop();
1603 }
1604 #ifndef PRODUCT
1605 if (TraceIterativeGVN) {
1606 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1607 con_type->dump(); tty->cr();
1608 }
1609 #endif //PRODUCT
1610 return con_type;
1611 }
1612 }
1613 return NULL;
1614 }
1615
1616 //------------------------------Value-----------------------------------------
1617 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1618 // Either input is TOP ==> the result is TOP
1619 Node* mem = in(MemNode::Memory);
1620 const Type *t1 = phase->type(mem);
1621 if (t1 == Type::TOP) return Type::TOP;
1622 Node* adr = in(MemNode::Address);
1623 const TypePtr* tp = phase->type(adr)->isa_ptr();
1624 if (tp == NULL || tp->empty()) return Type::TOP;
1625 int off = tp->offset();
1626 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1627 Compile* C = phase->C;
1628
1629 // Try to guess loaded type from pointer type
1630 if (tp->isa_aryptr()) {
1631 const TypeAryPtr* ary = tp->is_aryptr();
1632 const Type* t = ary->elem();
1633
1634 // Determine whether the reference is beyond the header or not, by comparing
1635 // the offset against the offset of the start of the array's data.
1636 // Different array types begin at slightly different offsets (12 vs. 16).
1637 // We choose T_BYTE as an example base type that is least restrictive
1638 // as to alignment, which will therefore produce the smallest
1639 // possible base offset.
1640 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1641 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1642
1643 // Try to constant-fold a stable array element.
1644 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
1645 // Make sure the reference is not into the header and the offset is constant
1646 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1647 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1648 if (con_type != NULL) {
1649 return con_type;
1650 }
1651 }
1652 }
1653
1654 // Don't do this for integer types. There is only potential profit if
1655 // the element type t is lower than _type; that is, for int types, if _type is
1656 // more restrictive than t. This only happens here if one is short and the other
1657 // char (both 16 bits), and in those cases we've made an intentional decision
1658 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1659 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1660 //
1661 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1662 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1663 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1664 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1665 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1666 // In fact, that could have been the original type of p1, and p1 could have
1667 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1668 // expression (LShiftL quux 3) independently optimized to the constant 8.
1669 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1670 && (_type->isa_vect() == NULL)
1671 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1672 // t might actually be lower than _type, if _type is a unique
1673 // concrete subclass of abstract class t.
1674 if (off_beyond_header) { // is the offset beyond the header?
1675 const Type* jt = t->join_speculative(_type);
1676 // In any case, do not allow the join, per se, to empty out the type.
1677 if (jt->empty() && !t->empty()) {
1678 // This can happen if a interface-typed array narrows to a class type.
1679 jt = _type;
1680 }
1681 #ifdef ASSERT
1682 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1683 // The pointers in the autobox arrays are always non-null
1684 Node* base = adr->in(AddPNode::Base);
1685 if ((base != NULL) && base->is_DecodeN()) {
1686 // Get LoadN node which loads IntegerCache.cache field
1687 base = base->in(1);
1688 }
1689 if ((base != NULL) && base->is_Con()) {
1690 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1691 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1692 // It could be narrow oop
1693 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1694 }
1695 }
1696 }
1697 #endif
1698 return jt;
1699 }
1700 }
1701 } else if (tp->base() == Type::InstPtr) {
1702 ciEnv* env = C->env();
1703 const TypeInstPtr* tinst = tp->is_instptr();
1704 ciKlass* klass = tinst->klass();
1705 assert( off != Type::OffsetBot ||
1706 // arrays can be cast to Objects
1707 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1708 // unsafe field access may not have a constant offset
1709 C->has_unsafe_access(),
1710 "Field accesses must be precise" );
1711 // For oop loads, we expect the _type to be precise
1712 if (klass == env->String_klass() &&
1713 adr->is_AddP() && off != Type::OffsetBot) {
1714 // For constant Strings treat the final fields as compile time constants.
1715 Node* base = adr->in(AddPNode::Base);
1716 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1717 if (t != NULL && t->singleton()) {
1718 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1719 if (field != NULL && field->is_final()) {
1720 ciObject* string = t->const_oop();
1721 ciConstant constant = string->as_instance()->field_value(field);
1722 if (constant.basic_type() == T_INT) {
1723 return TypeInt::make(constant.as_int());
1724 } else if (constant.basic_type() == T_ARRAY) {
1725 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1726 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1727 } else {
1728 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1729 }
1730 }
1731 }
1732 }
1733 }
1734 // Optimizations for constant objects
1735 ciObject* const_oop = tinst->const_oop();
1736 if (const_oop != NULL) {
1737 // For constant Boxed value treat the target field as a compile time constant.
1738 if (tinst->is_ptr_to_boxed_value()) {
1739 return tinst->get_const_boxed_value();
1740 } else
1741 // For constant CallSites treat the target field as a compile time constant.
1742 if (const_oop->is_call_site()) {
1743 ciCallSite* call_site = const_oop->as_call_site();
1744 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1745 if (field != NULL && field->is_call_site_target()) {
1746 ciMethodHandle* target = call_site->get_target();
1747 if (target != NULL) { // just in case
1748 ciConstant constant(T_OBJECT, target);
1749 const Type* t;
1750 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1751 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1752 } else {
1753 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1754 }
1755 // Add a dependence for invalidation of the optimization.
1756 if (!call_site->is_constant_call_site()) {
1757 C->dependencies()->assert_call_site_target_value(call_site, target);
1758 }
1759 return t;
1760 }
1761 }
1762 }
1763 }
1764 } else if (tp->base() == Type::KlassPtr) {
1765 assert( off != Type::OffsetBot ||
1766 // arrays can be cast to Objects
1767 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1768 // also allow array-loading from the primary supertype
1769 // array during subtype checks
1770 Opcode() == Op_LoadKlass,
1771 "Field accesses must be precise" );
1772 // For klass/static loads, we expect the _type to be precise
1773 }
1774
1775 const TypeKlassPtr *tkls = tp->isa_klassptr();
1776 if (tkls != NULL && !StressReflectiveCode) {
1777 ciKlass* klass = tkls->klass();
1778 if (klass->is_loaded() && tkls->klass_is_exact()) {
1779 // We are loading a field from a Klass metaobject whose identity
1780 // is known at compile time (the type is "exact" or "precise").
1781 // Check for fields we know are maintained as constants by the VM.
1782 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1783 // The field is Klass::_super_check_offset. Return its (constant) value.
1784 // (Folds up type checking code.)
1785 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1786 return TypeInt::make(klass->super_check_offset());
1787 }
1788 // Compute index into primary_supers array
1789 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1790 // Check for overflowing; use unsigned compare to handle the negative case.
1791 if( depth < ciKlass::primary_super_limit() ) {
1792 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1793 // (Folds up type checking code.)
1794 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1795 ciKlass *ss = klass->super_of_depth(depth);
1796 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1797 }
1798 const Type* aift = load_array_final_field(tkls, klass);
1799 if (aift != NULL) return aift;
1800 if (tkls->offset() == in_bytes(ArrayKlass::component_mirror_offset())
1801 && klass->is_array_klass()) {
1802 // The field is ArrayKlass::_component_mirror. Return its (constant) value.
1803 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1804 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1805 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1806 }
1807 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1808 // The field is Klass::_java_mirror. Return its (constant) value.
1809 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1810 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1811 return TypeInstPtr::make(klass->java_mirror());
1812 }
1813 }
1814
1815 // We can still check if we are loading from the primary_supers array at a
1816 // shallow enough depth. Even though the klass is not exact, entries less
1817 // than or equal to its super depth are correct.
1818 if (klass->is_loaded() ) {
1819 ciType *inner = klass;
1820 while( inner->is_obj_array_klass() )
1821 inner = inner->as_obj_array_klass()->base_element_type();
1822 if( inner->is_instance_klass() &&
1823 !inner->as_instance_klass()->flags().is_interface() ) {
1824 // Compute index into primary_supers array
1825 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1826 // Check for overflowing; use unsigned compare to handle the negative case.
1827 if( depth < ciKlass::primary_super_limit() &&
1828 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1829 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1830 // (Folds up type checking code.)
1831 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1832 ciKlass *ss = klass->super_of_depth(depth);
1833 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1834 }
1835 }
1836 }
1837
1838 // If the type is enough to determine that the thing is not an array,
1839 // we can give the layout_helper a positive interval type.
1840 // This will help short-circuit some reflective code.
1841 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1842 && !klass->is_array_klass() // not directly typed as an array
1843 && !klass->is_interface() // specifically not Serializable & Cloneable
1844 && !klass->is_java_lang_Object() // not the supertype of all T[]
1845 ) {
1846 // Note: When interfaces are reliable, we can narrow the interface
1847 // test to (klass != Serializable && klass != Cloneable).
1848 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1849 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1850 // The key property of this type is that it folds up tests
1851 // for array-ness, since it proves that the layout_helper is positive.
1852 // Thus, a generic value like the basic object layout helper works fine.
1853 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1854 }
1855 }
1856
1857 // If we are loading from a freshly-allocated object, produce a zero,
1858 // if the load is provably beyond the header of the object.
1859 // (Also allow a variable load from a fresh array to produce zero.)
1860 const TypeOopPtr *tinst = tp->isa_oopptr();
1861 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1862 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1863 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1864 Node* value = can_see_stored_value(mem,phase);
1865 if (value != NULL && value->is_Con()) {
1866 assert(value->bottom_type()->higher_equal(_type),"sanity");
1867 return value->bottom_type();
1868 }
1869 }
1870
1871 if (is_instance) {
1872 // If we have an instance type and our memory input is the
1873 // programs's initial memory state, there is no matching store,
1874 // so just return a zero of the appropriate type
1875 Node *mem = in(MemNode::Memory);
1876 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1877 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1878 return Type::get_zero_type(_type->basic_type());
1879 }
1880 }
1881 return _type;
1882 }
1883
1884 //------------------------------match_edge-------------------------------------
1885 // Do we Match on this edge index or not? Match only the address.
1886 uint LoadNode::match_edge(uint idx) const {
1887 return idx == MemNode::Address;
1888 }
1889
1890 //--------------------------LoadBNode::Ideal--------------------------------------
1891 //
1892 // If the previous store is to the same address as this load,
1893 // and the value stored was larger than a byte, replace this load
1894 // with the value stored truncated to a byte. If no truncation is
1895 // needed, the replacement is done in LoadNode::Identity().
1896 //
1897 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1898 Node* mem = in(MemNode::Memory);
1899 Node* value = can_see_stored_value(mem,phase);
1900 if( value && !phase->type(value)->higher_equal( _type ) ) {
1901 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1902 return new RShiftINode(result, phase->intcon(24));
1903 }
1904 // Identity call will handle the case where truncation is not needed.
1905 return LoadNode::Ideal(phase, can_reshape);
1906 }
1907
1908 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1909 Node* mem = in(MemNode::Memory);
1910 Node* value = can_see_stored_value(mem,phase);
1911 if (value != NULL && value->is_Con() &&
1912 !value->bottom_type()->higher_equal(_type)) {
1913 // If the input to the store does not fit with the load's result type,
1914 // it must be truncated. We can't delay until Ideal call since
1915 // a singleton Value is needed for split_thru_phi optimization.
1916 int con = value->get_int();
1917 return TypeInt::make((con << 24) >> 24);
1918 }
1919 return LoadNode::Value(phase);
1920 }
1921
1922 //--------------------------LoadUBNode::Ideal-------------------------------------
1923 //
1924 // If the previous store is to the same address as this load,
1925 // and the value stored was larger than a byte, replace this load
1926 // with the value stored truncated to a byte. If no truncation is
1927 // needed, the replacement is done in LoadNode::Identity().
1928 //
1929 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1930 Node* mem = in(MemNode::Memory);
1931 Node* value = can_see_stored_value(mem, phase);
1932 if (value && !phase->type(value)->higher_equal(_type))
1933 return new AndINode(value, phase->intcon(0xFF));
1934 // Identity call will handle the case where truncation is not needed.
1935 return LoadNode::Ideal(phase, can_reshape);
1936 }
1937
1938 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1939 Node* mem = in(MemNode::Memory);
1940 Node* value = can_see_stored_value(mem,phase);
1941 if (value != NULL && value->is_Con() &&
1942 !value->bottom_type()->higher_equal(_type)) {
1943 // If the input to the store does not fit with the load's result type,
1944 // it must be truncated. We can't delay until Ideal call since
1945 // a singleton Value is needed for split_thru_phi optimization.
1946 int con = value->get_int();
1947 return TypeInt::make(con & 0xFF);
1948 }
1949 return LoadNode::Value(phase);
1950 }
1951
1952 //--------------------------LoadUSNode::Ideal-------------------------------------
1953 //
1954 // If the previous store is to the same address as this load,
1955 // and the value stored was larger than a char, replace this load
1956 // with the value stored truncated to a char. If no truncation is
1957 // needed, the replacement is done in LoadNode::Identity().
1958 //
1959 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1960 Node* mem = in(MemNode::Memory);
1961 Node* value = can_see_stored_value(mem,phase);
1962 if( value && !phase->type(value)->higher_equal( _type ) )
1963 return new AndINode(value,phase->intcon(0xFFFF));
1964 // Identity call will handle the case where truncation is not needed.
1965 return LoadNode::Ideal(phase, can_reshape);
1966 }
1967
1968 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1969 Node* mem = in(MemNode::Memory);
1970 Node* value = can_see_stored_value(mem,phase);
1971 if (value != NULL && value->is_Con() &&
1972 !value->bottom_type()->higher_equal(_type)) {
1973 // If the input to the store does not fit with the load's result type,
1974 // it must be truncated. We can't delay until Ideal call since
1975 // a singleton Value is needed for split_thru_phi optimization.
1976 int con = value->get_int();
1977 return TypeInt::make(con & 0xFFFF);
1978 }
1979 return LoadNode::Value(phase);
1980 }
1981
1982 //--------------------------LoadSNode::Ideal--------------------------------------
1983 //
1984 // If the previous store is to the same address as this load,
1985 // and the value stored was larger than a short, replace this load
1986 // with the value stored truncated to a short. If no truncation is
1987 // needed, the replacement is done in LoadNode::Identity().
1988 //
1989 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1990 Node* mem = in(MemNode::Memory);
1991 Node* value = can_see_stored_value(mem,phase);
1992 if( value && !phase->type(value)->higher_equal( _type ) ) {
1993 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
1994 return new RShiftINode(result, phase->intcon(16));
1995 }
1996 // Identity call will handle the case where truncation is not needed.
1997 return LoadNode::Ideal(phase, can_reshape);
1998 }
1999
2000 const Type* LoadSNode::Value(PhaseTransform *phase) const {
2001 Node* mem = in(MemNode::Memory);
2002 Node* value = can_see_stored_value(mem,phase);
2003 if (value != NULL && value->is_Con() &&
2004 !value->bottom_type()->higher_equal(_type)) {
2005 // If the input to the store does not fit with the load's result type,
2006 // it must be truncated. We can't delay until Ideal call since
2007 // a singleton Value is needed for split_thru_phi optimization.
2008 int con = value->get_int();
2009 return TypeInt::make((con << 16) >> 16);
2010 }
2011 return LoadNode::Value(phase);
2012 }
2013
2014 //=============================================================================
2015 //----------------------------LoadKlassNode::make------------------------------
2016 // Polymorphic factory method:
2017 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
2018 Compile* C = gvn.C;
2019 Node *ctl = NULL;
2020 // sanity check the alias category against the created node type
2021 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2022 assert(adr_type != NULL, "expecting TypeKlassPtr");
2023 #ifdef _LP64
2024 if (adr_type->is_ptr_to_narrowklass()) {
2025 assert(UseCompressedClassPointers, "no compressed klasses");
2026 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2027 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2028 }
2029 #endif
2030 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2031 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2032 }
2033
2034 //------------------------------Value------------------------------------------
2035 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
2036 return klass_value_common(phase);
2037 }
2038
2039 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
2040 // Either input is TOP ==> the result is TOP
2041 const Type *t1 = phase->type( in(MemNode::Memory) );
2042 if (t1 == Type::TOP) return Type::TOP;
2043 Node *adr = in(MemNode::Address);
2044 const Type *t2 = phase->type( adr );
2045 if (t2 == Type::TOP) return Type::TOP;
2046 const TypePtr *tp = t2->is_ptr();
2047 if (TypePtr::above_centerline(tp->ptr()) ||
2048 tp->ptr() == TypePtr::Null) return Type::TOP;
2049
2050 // Return a more precise klass, if possible
2051 const TypeInstPtr *tinst = tp->isa_instptr();
2052 if (tinst != NULL) {
2053 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2054 int offset = tinst->offset();
2055 if (ik == phase->C->env()->Class_klass()
2056 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2057 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2058 // We are loading a special hidden field from a Class mirror object,
2059 // the field which points to the VM's Klass metaobject.
2060 ciType* t = tinst->java_mirror_type();
2061 // java_mirror_type returns non-null for compile-time Class constants.
2062 if (t != NULL) {
2063 // constant oop => constant klass
2064 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2065 if (t->is_void()) {
2066 // We cannot create a void array. Since void is a primitive type return null
2067 // klass. Users of this result need to do a null check on the returned klass.
2068 return TypePtr::NULL_PTR;
2069 }
2070 return TypeKlassPtr::make(ciArrayKlass::make(t));
2071 }
2072 if (!t->is_klass()) {
2073 // a primitive Class (e.g., int.class) has NULL for a klass field
2074 return TypePtr::NULL_PTR;
2075 }
2076 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2077 return TypeKlassPtr::make(t->as_klass());
2078 }
2079 // non-constant mirror, so we can't tell what's going on
2080 }
2081 if( !ik->is_loaded() )
2082 return _type; // Bail out if not loaded
2083 if (offset == oopDesc::klass_offset_in_bytes()) {
2084 if (tinst->klass_is_exact()) {
2085 return TypeKlassPtr::make(ik);
2086 }
2087 // See if we can become precise: no subklasses and no interface
2088 // (Note: We need to support verified interfaces.)
2089 if (!ik->is_interface() && !ik->has_subklass()) {
2090 //assert(!UseExactTypes, "this code should be useless with exact types");
2091 // Add a dependence; if any subclass added we need to recompile
2092 if (!ik->is_final()) {
2093 // %%% should use stronger assert_unique_concrete_subtype instead
2094 phase->C->dependencies()->assert_leaf_type(ik);
2095 }
2096 // Return precise klass
2097 return TypeKlassPtr::make(ik);
2098 }
2099
2100 // Return root of possible klass
2101 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2102 }
2103 }
2104
2105 // Check for loading klass from an array
2106 const TypeAryPtr *tary = tp->isa_aryptr();
2107 if( tary != NULL ) {
2108 ciKlass *tary_klass = tary->klass();
2109 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2110 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2111 if (tary->klass_is_exact()) {
2112 return TypeKlassPtr::make(tary_klass);
2113 }
2114 ciArrayKlass *ak = tary->klass()->as_array_klass();
2115 // If the klass is an object array, we defer the question to the
2116 // array component klass.
2117 if( ak->is_obj_array_klass() ) {
2118 assert( ak->is_loaded(), "" );
2119 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2120 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2121 ciInstanceKlass* ik = base_k->as_instance_klass();
2122 // See if we can become precise: no subklasses and no interface
2123 if (!ik->is_interface() && !ik->has_subklass()) {
2124 //assert(!UseExactTypes, "this code should be useless with exact types");
2125 // Add a dependence; if any subclass added we need to recompile
2126 if (!ik->is_final()) {
2127 phase->C->dependencies()->assert_leaf_type(ik);
2128 }
2129 // Return precise array klass
2130 return TypeKlassPtr::make(ak);
2131 }
2132 }
2133 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2134 } else { // Found a type-array?
2135 //assert(!UseExactTypes, "this code should be useless with exact types");
2136 assert( ak->is_type_array_klass(), "" );
2137 return TypeKlassPtr::make(ak); // These are always precise
2138 }
2139 }
2140 }
2141
2142 // Check for loading klass from an array klass
2143 const TypeKlassPtr *tkls = tp->isa_klassptr();
2144 if (tkls != NULL && !StressReflectiveCode) {
2145 ciKlass* klass = tkls->klass();
2146 if( !klass->is_loaded() )
2147 return _type; // Bail out if not loaded
2148 if( klass->is_obj_array_klass() &&
2149 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2150 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2151 // // Always returning precise element type is incorrect,
2152 // // e.g., element type could be object and array may contain strings
2153 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2154
2155 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2156 // according to the element type's subclassing.
2157 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2158 }
2159 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2160 tkls->offset() == in_bytes(Klass::super_offset())) {
2161 ciKlass* sup = klass->as_instance_klass()->super();
2162 // The field is Klass::_super. Return its (constant) value.
2163 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2164 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2165 }
2166 }
2167
2168 // Bailout case
2169 return LoadNode::Value(phase);
2170 }
2171
2172 //------------------------------Identity---------------------------------------
2173 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2174 // Also feed through the klass in Allocate(...klass...)._klass.
2175 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2176 return klass_identity_common(phase);
2177 }
2178
2179 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2180 Node* x = LoadNode::Identity(phase);
2181 if (x != this) return x;
2182
2183 // Take apart the address into an oop and and offset.
2184 // Return 'this' if we cannot.
2185 Node* adr = in(MemNode::Address);
2186 intptr_t offset = 0;
2187 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2188 if (base == NULL) return this;
2189 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2190 if (toop == NULL) return this;
2191
2192 // We can fetch the klass directly through an AllocateNode.
2193 // This works even if the klass is not constant (clone or newArray).
2194 if (offset == oopDesc::klass_offset_in_bytes()) {
2195 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2196 if (allocated_klass != NULL) {
2197 return allocated_klass;
2198 }
2199 }
2200
2201 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2202 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass.
2203 // See inline_native_Class_query for occurrences of these patterns.
2204 // Java Example: x.getClass().isAssignableFrom(y)
2205 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2206 //
2207 // This improves reflective code, often making the Class
2208 // mirror go completely dead. (Current exception: Class
2209 // mirrors may appear in debug info, but we could clean them out by
2210 // introducing a new debug info operator for Klass*.java_mirror).
2211 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2212 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2213 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2214 // We are loading a special hidden field from a Class mirror,
2215 // the field which points to its Klass or ArrayKlass metaobject.
2216 if (base->is_Load()) {
2217 Node* adr2 = base->in(MemNode::Address);
2218 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2219 if (tkls != NULL && !tkls->empty()
2220 && (tkls->klass()->is_instance_klass() ||
2221 tkls->klass()->is_array_klass())
2222 && adr2->is_AddP()
2223 ) {
2224 int mirror_field = in_bytes(Klass::java_mirror_offset());
2225 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2226 mirror_field = in_bytes(ArrayKlass::component_mirror_offset());
2227 }
2228 if (tkls->offset() == mirror_field) {
2229 return adr2->in(AddPNode::Base);
2230 }
2231 }
2232 }
2233 }
2234
2235 return this;
2236 }
2237
2238
2239 //------------------------------Value------------------------------------------
2240 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2241 const Type *t = klass_value_common(phase);
2242 if (t == Type::TOP)
2243 return t;
2244
2245 return t->make_narrowklass();
2246 }
2247
2248 //------------------------------Identity---------------------------------------
2249 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2250 // Also feed through the klass in Allocate(...klass...)._klass.
2251 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2252 Node *x = klass_identity_common(phase);
2253
2254 const Type *t = phase->type( x );
2255 if( t == Type::TOP ) return x;
2256 if( t->isa_narrowklass()) return x;
2257 assert (!t->isa_narrowoop(), "no narrow oop here");
2258
2259 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2260 }
2261
2262 //------------------------------Value-----------------------------------------
2263 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2264 // Either input is TOP ==> the result is TOP
2265 const Type *t1 = phase->type( in(MemNode::Memory) );
2266 if( t1 == Type::TOP ) return Type::TOP;
2267 Node *adr = in(MemNode::Address);
2268 const Type *t2 = phase->type( adr );
2269 if( t2 == Type::TOP ) return Type::TOP;
2270 const TypePtr *tp = t2->is_ptr();
2271 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2272 const TypeAryPtr *tap = tp->isa_aryptr();
2273 if( !tap ) return _type;
2274 return tap->size();
2275 }
2276
2277 //-------------------------------Ideal---------------------------------------
2278 // Feed through the length in AllocateArray(...length...)._length.
2279 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2280 Node* p = MemNode::Ideal_common(phase, can_reshape);
2281 if (p) return (p == NodeSentinel) ? NULL : p;
2282
2283 // Take apart the address into an oop and and offset.
2284 // Return 'this' if we cannot.
2285 Node* adr = in(MemNode::Address);
2286 intptr_t offset = 0;
2287 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2288 if (base == NULL) return NULL;
2289 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2290 if (tary == NULL) return NULL;
2291
2292 // We can fetch the length directly through an AllocateArrayNode.
2293 // This works even if the length is not constant (clone or newArray).
2294 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2295 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2296 if (alloc != NULL) {
2297 Node* allocated_length = alloc->Ideal_length();
2298 Node* len = alloc->make_ideal_length(tary, phase);
2299 if (allocated_length != len) {
2300 // New CastII improves on this.
2301 return len;
2302 }
2303 }
2304 }
2305
2306 return NULL;
2307 }
2308
2309 //------------------------------Identity---------------------------------------
2310 // Feed through the length in AllocateArray(...length...)._length.
2311 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2312 Node* x = LoadINode::Identity(phase);
2313 if (x != this) return x;
2314
2315 // Take apart the address into an oop and and offset.
2316 // Return 'this' if we cannot.
2317 Node* adr = in(MemNode::Address);
2318 intptr_t offset = 0;
2319 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2320 if (base == NULL) return this;
2321 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2322 if (tary == NULL) return this;
2323
2324 // We can fetch the length directly through an AllocateArrayNode.
2325 // This works even if the length is not constant (clone or newArray).
2326 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2327 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2328 if (alloc != NULL) {
2329 Node* allocated_length = alloc->Ideal_length();
2330 // Do not allow make_ideal_length to allocate a CastII node.
2331 Node* len = alloc->make_ideal_length(tary, phase, false);
2332 if (allocated_length == len) {
2333 // Return allocated_length only if it would not be improved by a CastII.
2334 return allocated_length;
2335 }
2336 }
2337 }
2338
2339 return this;
2340
2341 }
2342
2343 //=============================================================================
2344 //---------------------------StoreNode::make-----------------------------------
2345 // Polymorphic factory method:
2346 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2347 assert((mo == unordered || mo == release), "unexpected");
2348 Compile* C = gvn.C;
2349 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2350 ctl != NULL, "raw memory operations should have control edge");
2351
2352 switch (bt) {
2353 case T_BOOLEAN:
2354 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2355 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2356 case T_CHAR:
2357 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2358 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2359 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2360 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2361 case T_METADATA:
2362 case T_ADDRESS:
2363 case T_OBJECT:
2364 #ifdef _LP64
2365 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2366 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2367 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2368 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2369 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2370 adr->bottom_type()->isa_rawptr())) {
2371 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2372 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2373 }
2374 #endif
2375 {
2376 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2377 }
2378 }
2379 ShouldNotReachHere();
2380 return (StoreNode*)NULL;
2381 }
2382
2383 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2384 bool require_atomic = true;
2385 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2386 }
2387
2388 StoreDNode* StoreDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2389 bool require_atomic = true;
2390 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2391 }
2392
2393
2394 //--------------------------bottom_type----------------------------------------
2395 const Type *StoreNode::bottom_type() const {
2396 return Type::MEMORY;
2397 }
2398
2399 //------------------------------hash-------------------------------------------
2400 uint StoreNode::hash() const {
2401 // unroll addition of interesting fields
2402 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2403
2404 // Since they are not commoned, do not hash them:
2405 return NO_HASH;
2406 }
2407
2408 //------------------------------Ideal------------------------------------------
2409 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2410 // When a store immediately follows a relevant allocation/initialization,
2411 // try to capture it into the initialization, or hoist it above.
2412 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2413 Node* p = MemNode::Ideal_common(phase, can_reshape);
2414 if (p) return (p == NodeSentinel) ? NULL : p;
2415
2416 Node* mem = in(MemNode::Memory);
2417 Node* address = in(MemNode::Address);
2418
2419 // Back-to-back stores to same address? Fold em up. Generally
2420 // unsafe if I have intervening uses... Also disallowed for StoreCM
2421 // since they must follow each StoreP operation. Redundant StoreCMs
2422 // are eliminated just before matching in final_graph_reshape.
2423 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2424 mem->Opcode() != Op_StoreCM) {
2425 // Looking at a dead closed cycle of memory?
2426 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2427
2428 assert(Opcode() == mem->Opcode() ||
2429 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2430 "no mismatched stores, except on raw memory");
2431
2432 if (mem->outcnt() == 1 && // check for intervening uses
2433 mem->as_Store()->memory_size() <= this->memory_size()) {
2434 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2435 // For example, 'mem' might be the final state at a conditional return.
2436 // Or, 'mem' might be used by some node which is live at the same time
2437 // 'this' is live, which might be unschedulable. So, require exactly
2438 // ONE user, the 'this' store, until such time as we clone 'mem' for
2439 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2440 if (can_reshape) { // (%%% is this an anachronism?)
2441 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2442 phase->is_IterGVN());
2443 } else {
2444 // It's OK to do this in the parser, since DU info is always accurate,
2445 // and the parser always refers to nodes via SafePointNode maps.
2446 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2447 }
2448 return this;
2449 }
2450 }
2451
2452 // Capture an unaliased, unconditional, simple store into an initializer.
2453 // Or, if it is independent of the allocation, hoist it above the allocation.
2454 if (ReduceFieldZeroing && /*can_reshape &&*/
2455 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2456 InitializeNode* init = mem->in(0)->as_Initialize();
2457 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2458 if (offset > 0) {
2459 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2460 // If the InitializeNode captured me, it made a raw copy of me,
2461 // and I need to disappear.
2462 if (moved != NULL) {
2463 // %%% hack to ensure that Ideal returns a new node:
2464 mem = MergeMemNode::make(phase->C, mem);
2465 return mem; // fold me away
2466 }
2467 }
2468 }
2469
2470 return NULL; // No further progress
2471 }
2472
2473 //------------------------------Value-----------------------------------------
2474 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2475 // Either input is TOP ==> the result is TOP
2476 const Type *t1 = phase->type( in(MemNode::Memory) );
2477 if( t1 == Type::TOP ) return Type::TOP;
2478 const Type *t2 = phase->type( in(MemNode::Address) );
2479 if( t2 == Type::TOP ) return Type::TOP;
2480 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2481 if( t3 == Type::TOP ) return Type::TOP;
2482 return Type::MEMORY;
2483 }
2484
2485 //------------------------------Identity---------------------------------------
2486 // Remove redundant stores:
2487 // Store(m, p, Load(m, p)) changes to m.
2488 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2489 Node *StoreNode::Identity( PhaseTransform *phase ) {
2490 Node* mem = in(MemNode::Memory);
2491 Node* adr = in(MemNode::Address);
2492 Node* val = in(MemNode::ValueIn);
2493
2494 // Load then Store? Then the Store is useless
2495 if (val->is_Load() &&
2496 val->in(MemNode::Address)->eqv_uncast(adr) &&
2497 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2498 val->as_Load()->store_Opcode() == Opcode()) {
2499 return mem;
2500 }
2501
2502 // Two stores in a row of the same value?
2503 if (mem->is_Store() &&
2504 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2505 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2506 mem->Opcode() == Opcode()) {
2507 return mem;
2508 }
2509
2510 // Store of zero anywhere into a freshly-allocated object?
2511 // Then the store is useless.
2512 // (It must already have been captured by the InitializeNode.)
2513 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2514 // a newly allocated object is already all-zeroes everywhere
2515 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2516 return mem;
2517 }
2518
2519 // the store may also apply to zero-bits in an earlier object
2520 Node* prev_mem = find_previous_store(phase);
2521 // Steps (a), (b): Walk past independent stores to find an exact match.
2522 if (prev_mem != NULL) {
2523 Node* prev_val = can_see_stored_value(prev_mem, phase);
2524 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2525 // prev_val and val might differ by a cast; it would be good
2526 // to keep the more informative of the two.
2527 return mem;
2528 }
2529 }
2530 }
2531
2532 return this;
2533 }
2534
2535 //------------------------------match_edge-------------------------------------
2536 // Do we Match on this edge index or not? Match only memory & value
2537 uint StoreNode::match_edge(uint idx) const {
2538 return idx == MemNode::Address || idx == MemNode::ValueIn;
2539 }
2540
2541 //------------------------------cmp--------------------------------------------
2542 // Do not common stores up together. They generally have to be split
2543 // back up anyways, so do not bother.
2544 uint StoreNode::cmp( const Node &n ) const {
2545 return (&n == this); // Always fail except on self
2546 }
2547
2548 //------------------------------Ideal_masked_input-----------------------------
2549 // Check for a useless mask before a partial-word store
2550 // (StoreB ... (AndI valIn conIa) )
2551 // If (conIa & mask == mask) this simplifies to
2552 // (StoreB ... (valIn) )
2553 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2554 Node *val = in(MemNode::ValueIn);
2555 if( val->Opcode() == Op_AndI ) {
2556 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2557 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2558 set_req(MemNode::ValueIn, val->in(1));
2559 return this;
2560 }
2561 }
2562 return NULL;
2563 }
2564
2565
2566 //------------------------------Ideal_sign_extended_input----------------------
2567 // Check for useless sign-extension before a partial-word store
2568 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2569 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2570 // (StoreB ... (valIn) )
2571 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2572 Node *val = in(MemNode::ValueIn);
2573 if( val->Opcode() == Op_RShiftI ) {
2574 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2575 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2576 Node *shl = val->in(1);
2577 if( shl->Opcode() == Op_LShiftI ) {
2578 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2579 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2580 set_req(MemNode::ValueIn, shl->in(1));
2581 return this;
2582 }
2583 }
2584 }
2585 }
2586 return NULL;
2587 }
2588
2589 //------------------------------value_never_loaded-----------------------------------
2590 // Determine whether there are any possible loads of the value stored.
2591 // For simplicity, we actually check if there are any loads from the
2592 // address stored to, not just for loads of the value stored by this node.
2593 //
2594 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2595 Node *adr = in(Address);
2596 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2597 if (adr_oop == NULL)
2598 return false;
2599 if (!adr_oop->is_known_instance_field())
2600 return false; // if not a distinct instance, there may be aliases of the address
2601 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2602 Node *use = adr->fast_out(i);
2603 int opc = use->Opcode();
2604 if (use->is_Load() || use->is_LoadStore()) {
2605 return false;
2606 }
2607 }
2608 return true;
2609 }
2610
2611 //=============================================================================
2612 //------------------------------Ideal------------------------------------------
2613 // If the store is from an AND mask that leaves the low bits untouched, then
2614 // we can skip the AND operation. If the store is from a sign-extension
2615 // (a left shift, then right shift) we can skip both.
2616 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2617 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2618 if( progress != NULL ) return progress;
2619
2620 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2621 if( progress != NULL ) return progress;
2622
2623 // Finally check the default case
2624 return StoreNode::Ideal(phase, can_reshape);
2625 }
2626
2627 //=============================================================================
2628 //------------------------------Ideal------------------------------------------
2629 // If the store is from an AND mask that leaves the low bits untouched, then
2630 // we can skip the AND operation
2631 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2632 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2633 if( progress != NULL ) return progress;
2634
2635 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2636 if( progress != NULL ) return progress;
2637
2638 // Finally check the default case
2639 return StoreNode::Ideal(phase, can_reshape);
2640 }
2641
2642 //=============================================================================
2643 //------------------------------Identity---------------------------------------
2644 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2645 // No need to card mark when storing a null ptr
2646 Node* my_store = in(MemNode::OopStore);
2647 if (my_store->is_Store()) {
2648 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2649 if( t1 == TypePtr::NULL_PTR ) {
2650 return in(MemNode::Memory);
2651 }
2652 }
2653 return this;
2654 }
2655
2656 //=============================================================================
2657 //------------------------------Ideal---------------------------------------
2658 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2659 Node* progress = StoreNode::Ideal(phase, can_reshape);
2660 if (progress != NULL) return progress;
2661
2662 Node* my_store = in(MemNode::OopStore);
2663 if (my_store->is_MergeMem()) {
2664 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2665 set_req(MemNode::OopStore, mem);
2666 return this;
2667 }
2668
2669 return NULL;
2670 }
2671
2672 //------------------------------Value-----------------------------------------
2673 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2674 // Either input is TOP ==> the result is TOP
2675 const Type *t = phase->type( in(MemNode::Memory) );
2676 if( t == Type::TOP ) return Type::TOP;
2677 t = phase->type( in(MemNode::Address) );
2678 if( t == Type::TOP ) return Type::TOP;
2679 t = phase->type( in(MemNode::ValueIn) );
2680 if( t == Type::TOP ) return Type::TOP;
2681 // If extra input is TOP ==> the result is TOP
2682 t = phase->type( in(MemNode::OopStore) );
2683 if( t == Type::TOP ) return Type::TOP;
2684
2685 return StoreNode::Value( phase );
2686 }
2687
2688
2689 //=============================================================================
2690 //----------------------------------SCMemProjNode------------------------------
2691 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2692 {
2693 return bottom_type();
2694 }
2695
2696 //=============================================================================
2697 //----------------------------------LoadStoreNode------------------------------
2698 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2699 : Node(required),
2700 _type(rt),
2701 _adr_type(at)
2702 {
2703 init_req(MemNode::Control, c );
2704 init_req(MemNode::Memory , mem);
2705 init_req(MemNode::Address, adr);
2706 init_req(MemNode::ValueIn, val);
2707 init_class_id(Class_LoadStore);
2708 }
2709
2710 uint LoadStoreNode::ideal_reg() const {
2711 return _type->ideal_reg();
2712 }
2713
2714 bool LoadStoreNode::result_not_used() const {
2715 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2716 Node *x = fast_out(i);
2717 if (x->Opcode() == Op_SCMemProj) continue;
2718 return false;
2719 }
2720 return true;
2721 }
2722
2723 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2724
2725 //=============================================================================
2726 //----------------------------------LoadStoreConditionalNode--------------------
2727 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2728 init_req(ExpectedIn, ex );
2729 }
2730
2731 //=============================================================================
2732 //-------------------------------adr_type--------------------------------------
2733 // Do we Match on this edge index or not? Do not match memory
2734 const TypePtr* ClearArrayNode::adr_type() const {
2735 Node *adr = in(3);
2736 return MemNode::calculate_adr_type(adr->bottom_type());
2737 }
2738
2739 //------------------------------match_edge-------------------------------------
2740 // Do we Match on this edge index or not? Do not match memory
2741 uint ClearArrayNode::match_edge(uint idx) const {
2742 return idx > 1;
2743 }
2744
2745 //------------------------------Identity---------------------------------------
2746 // Clearing a zero length array does nothing
2747 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2748 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2749 }
2750
2751 //------------------------------Idealize---------------------------------------
2752 // Clearing a short array is faster with stores
2753 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2754 const int unit = BytesPerLong;
2755 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2756 if (!t) return NULL;
2757 if (!t->is_con()) return NULL;
2758 intptr_t raw_count = t->get_con();
2759 intptr_t size = raw_count;
2760 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2761 // Clearing nothing uses the Identity call.
2762 // Negative clears are possible on dead ClearArrays
2763 // (see jck test stmt114.stmt11402.val).
2764 if (size <= 0 || size % unit != 0) return NULL;
2765 intptr_t count = size / unit;
2766 // Length too long; use fast hardware clear
2767 if (size > Matcher::init_array_short_size) return NULL;
2768 Node *mem = in(1);
2769 if( phase->type(mem)==Type::TOP ) return NULL;
2770 Node *adr = in(3);
2771 const Type* at = phase->type(adr);
2772 if( at==Type::TOP ) return NULL;
2773 const TypePtr* atp = at->isa_ptr();
2774 // adjust atp to be the correct array element address type
2775 if (atp == NULL) atp = TypePtr::BOTTOM;
2776 else atp = atp->add_offset(Type::OffsetBot);
2777 // Get base for derived pointer purposes
2778 if( adr->Opcode() != Op_AddP ) Unimplemented();
2779 Node *base = adr->in(1);
2780
2781 Node *zero = phase->makecon(TypeLong::ZERO);
2782 Node *off = phase->MakeConX(BytesPerLong);
2783 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2784 count--;
2785 while( count-- ) {
2786 mem = phase->transform(mem);
2787 adr = phase->transform(new AddPNode(base,adr,off));
2788 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2789 }
2790 return mem;
2791 }
2792
2793 //----------------------------step_through----------------------------------
2794 // Return allocation input memory edge if it is different instance
2795 // or itself if it is the one we are looking for.
2796 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2797 Node* n = *np;
2798 assert(n->is_ClearArray(), "sanity");
2799 intptr_t offset;
2800 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2801 // This method is called only before Allocate nodes are expanded during
2802 // macro nodes expansion. Before that ClearArray nodes are only generated
2803 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2804 assert(alloc != NULL, "should have allocation");
2805 if (alloc->_idx == instance_id) {
2806 // Can not bypass initialization of the instance we are looking for.
2807 return false;
2808 }
2809 // Otherwise skip it.
2810 InitializeNode* init = alloc->initialization();
2811 if (init != NULL)
2812 *np = init->in(TypeFunc::Memory);
2813 else
2814 *np = alloc->in(TypeFunc::Memory);
2815 return true;
2816 }
2817
2818 //----------------------------clear_memory-------------------------------------
2819 // Generate code to initialize object storage to zero.
2820 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2821 intptr_t start_offset,
2822 Node* end_offset,
2823 PhaseGVN* phase) {
2824 Compile* C = phase->C;
2825 intptr_t offset = start_offset;
2826
2827 int unit = BytesPerLong;
2828 if ((offset % unit) != 0) {
2829 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2830 adr = phase->transform(adr);
2831 const TypePtr* atp = TypeRawPtr::BOTTOM;
2832 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2833 mem = phase->transform(mem);
2834 offset += BytesPerInt;
2835 }
2836 assert((offset % unit) == 0, "");
2837
2838 // Initialize the remaining stuff, if any, with a ClearArray.
2839 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2840 }
2841
2842 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2843 Node* start_offset,
2844 Node* end_offset,
2845 PhaseGVN* phase) {
2846 if (start_offset == end_offset) {
2847 // nothing to do
2848 return mem;
2849 }
2850
2851 Compile* C = phase->C;
2852 int unit = BytesPerLong;
2853 Node* zbase = start_offset;
2854 Node* zend = end_offset;
2855
2856 // Scale to the unit required by the CPU:
2857 if (!Matcher::init_array_count_is_in_bytes) {
2858 Node* shift = phase->intcon(exact_log2(unit));
2859 zbase = phase->transform(new URShiftXNode(zbase, shift) );
2860 zend = phase->transform(new URShiftXNode(zend, shift) );
2861 }
2862
2863 // Bulk clear double-words
2864 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
2865 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
2866 mem = new ClearArrayNode(ctl, mem, zsize, adr);
2867 return phase->transform(mem);
2868 }
2869
2870 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2871 intptr_t start_offset,
2872 intptr_t end_offset,
2873 PhaseGVN* phase) {
2874 if (start_offset == end_offset) {
2875 // nothing to do
2876 return mem;
2877 }
2878
2879 Compile* C = phase->C;
2880 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2881 intptr_t done_offset = end_offset;
2882 if ((done_offset % BytesPerLong) != 0) {
2883 done_offset -= BytesPerInt;
2884 }
2885 if (done_offset > start_offset) {
2886 mem = clear_memory(ctl, mem, dest,
2887 start_offset, phase->MakeConX(done_offset), phase);
2888 }
2889 if (done_offset < end_offset) { // emit the final 32-bit store
2890 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
2891 adr = phase->transform(adr);
2892 const TypePtr* atp = TypeRawPtr::BOTTOM;
2893 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2894 mem = phase->transform(mem);
2895 done_offset += BytesPerInt;
2896 }
2897 assert(done_offset == end_offset, "");
2898 return mem;
2899 }
2900
2901 //=============================================================================
2902 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2903 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2904 _adr_type(C->get_adr_type(alias_idx))
2905 {
2906 init_class_id(Class_MemBar);
2907 Node* top = C->top();
2908 init_req(TypeFunc::I_O,top);
2909 init_req(TypeFunc::FramePtr,top);
2910 init_req(TypeFunc::ReturnAdr,top);
2911 if (precedent != NULL)
2912 init_req(TypeFunc::Parms, precedent);
2913 }
2914
2915 //------------------------------cmp--------------------------------------------
2916 uint MemBarNode::hash() const { return NO_HASH; }
2917 uint MemBarNode::cmp( const Node &n ) const {
2918 return (&n == this); // Always fail except on self
2919 }
2920
2921 //------------------------------make-------------------------------------------
2922 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2923 switch (opcode) {
2924 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
2925 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
2926 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
2927 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
2928 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
2929 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
2930 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
2931 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
2932 case Op_Initialize: return new InitializeNode(C, atp, pn);
2933 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
2934 default: ShouldNotReachHere(); return NULL;
2935 }
2936 }
2937
2938 //------------------------------Ideal------------------------------------------
2939 // Return a node which is more "ideal" than the current node. Strip out
2940 // control copies
2941 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2942 if (remove_dead_region(phase, can_reshape)) return this;
2943 // Don't bother trying to transform a dead node
2944 if (in(0) && in(0)->is_top()) {
2945 return NULL;
2946 }
2947
2948 // Eliminate volatile MemBars for scalar replaced objects.
2949 if (can_reshape && req() == (Precedent+1)) {
2950 bool eliminate = false;
2951 int opc = Opcode();
2952 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2953 // Volatile field loads and stores.
2954 Node* my_mem = in(MemBarNode::Precedent);
2955 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
2956 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
2957 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
2958 // replace this Precedent (decodeN) with the Load instead.
2959 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
2960 Node* load_node = my_mem->in(1);
2961 set_req(MemBarNode::Precedent, load_node);
2962 phase->is_IterGVN()->_worklist.push(my_mem);
2963 my_mem = load_node;
2964 } else {
2965 assert(my_mem->unique_out() == this, "sanity");
2966 del_req(Precedent);
2967 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
2968 my_mem = NULL;
2969 }
2970 }
2971 if (my_mem != NULL && my_mem->is_Mem()) {
2972 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2973 // Check for scalar replaced object reference.
2974 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2975 t_oop->offset() != Type::OffsetBot &&
2976 t_oop->offset() != Type::OffsetTop) {
2977 eliminate = true;
2978 }
2979 }
2980 } else if (opc == Op_MemBarRelease) {
2981 // Final field stores.
2982 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
2983 if ((alloc != NULL) && alloc->is_Allocate() &&
2984 alloc->as_Allocate()->_is_non_escaping) {
2985 // The allocated object does not escape.
2986 eliminate = true;
2987 }
2988 }
2989 if (eliminate) {
2990 // Replace MemBar projections by its inputs.
2991 PhaseIterGVN* igvn = phase->is_IterGVN();
2992 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2993 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2994 // Must return either the original node (now dead) or a new node
2995 // (Do not return a top here, since that would break the uniqueness of top.)
2996 return new ConINode(TypeInt::ZERO);
2997 }
2998 }
2999 return NULL;
3000 }
3001
3002 //------------------------------Value------------------------------------------
3003 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
3004 if( !in(0) ) return Type::TOP;
3005 if( phase->type(in(0)) == Type::TOP )
3006 return Type::TOP;
3007 return TypeTuple::MEMBAR;
3008 }
3009
3010 //------------------------------match------------------------------------------
3011 // Construct projections for memory.
3012 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3013 switch (proj->_con) {
3014 case TypeFunc::Control:
3015 case TypeFunc::Memory:
3016 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3017 }
3018 ShouldNotReachHere();
3019 return NULL;
3020 }
3021
3022 //===========================InitializeNode====================================
3023 // SUMMARY:
3024 // This node acts as a memory barrier on raw memory, after some raw stores.
3025 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3026 // The Initialize can 'capture' suitably constrained stores as raw inits.
3027 // It can coalesce related raw stores into larger units (called 'tiles').
3028 // It can avoid zeroing new storage for memory units which have raw inits.
3029 // At macro-expansion, it is marked 'complete', and does not optimize further.
3030 //
3031 // EXAMPLE:
3032 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3033 // ctl = incoming control; mem* = incoming memory
3034 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3035 // First allocate uninitialized memory and fill in the header:
3036 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3037 // ctl := alloc.Control; mem* := alloc.Memory*
3038 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3039 // Then initialize to zero the non-header parts of the raw memory block:
3040 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3041 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3042 // After the initialize node executes, the object is ready for service:
3043 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3044 // Suppose its body is immediately initialized as {1,2}:
3045 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3046 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3047 // mem.SLICE(#short[*]) := store2
3048 //
3049 // DETAILS:
3050 // An InitializeNode collects and isolates object initialization after
3051 // an AllocateNode and before the next possible safepoint. As a
3052 // memory barrier (MemBarNode), it keeps critical stores from drifting
3053 // down past any safepoint or any publication of the allocation.
3054 // Before this barrier, a newly-allocated object may have uninitialized bits.
3055 // After this barrier, it may be treated as a real oop, and GC is allowed.
3056 //
3057 // The semantics of the InitializeNode include an implicit zeroing of
3058 // the new object from object header to the end of the object.
3059 // (The object header and end are determined by the AllocateNode.)
3060 //
3061 // Certain stores may be added as direct inputs to the InitializeNode.
3062 // These stores must update raw memory, and they must be to addresses
3063 // derived from the raw address produced by AllocateNode, and with
3064 // a constant offset. They must be ordered by increasing offset.
3065 // The first one is at in(RawStores), the last at in(req()-1).
3066 // Unlike most memory operations, they are not linked in a chain,
3067 // but are displayed in parallel as users of the rawmem output of
3068 // the allocation.
3069 //
3070 // (See comments in InitializeNode::capture_store, which continue
3071 // the example given above.)
3072 //
3073 // When the associated Allocate is macro-expanded, the InitializeNode
3074 // may be rewritten to optimize collected stores. A ClearArrayNode
3075 // may also be created at that point to represent any required zeroing.
3076 // The InitializeNode is then marked 'complete', prohibiting further
3077 // capturing of nearby memory operations.
3078 //
3079 // During macro-expansion, all captured initializations which store
3080 // constant values of 32 bits or smaller are coalesced (if advantageous)
3081 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3082 // initialized in fewer memory operations. Memory words which are
3083 // covered by neither tiles nor non-constant stores are pre-zeroed
3084 // by explicit stores of zero. (The code shape happens to do all
3085 // zeroing first, then all other stores, with both sequences occurring
3086 // in order of ascending offsets.)
3087 //
3088 // Alternatively, code may be inserted between an AllocateNode and its
3089 // InitializeNode, to perform arbitrary initialization of the new object.
3090 // E.g., the object copying intrinsics insert complex data transfers here.
3091 // The initialization must then be marked as 'complete' disable the
3092 // built-in zeroing semantics and the collection of initializing stores.
3093 //
3094 // While an InitializeNode is incomplete, reads from the memory state
3095 // produced by it are optimizable if they match the control edge and
3096 // new oop address associated with the allocation/initialization.
3097 // They return a stored value (if the offset matches) or else zero.
3098 // A write to the memory state, if it matches control and address,
3099 // and if it is to a constant offset, may be 'captured' by the
3100 // InitializeNode. It is cloned as a raw memory operation and rewired
3101 // inside the initialization, to the raw oop produced by the allocation.
3102 // Operations on addresses which are provably distinct (e.g., to
3103 // other AllocateNodes) are allowed to bypass the initialization.
3104 //
3105 // The effect of all this is to consolidate object initialization
3106 // (both arrays and non-arrays, both piecewise and bulk) into a
3107 // single location, where it can be optimized as a unit.
3108 //
3109 // Only stores with an offset less than TrackedInitializationLimit words
3110 // will be considered for capture by an InitializeNode. This puts a
3111 // reasonable limit on the complexity of optimized initializations.
3112
3113 //---------------------------InitializeNode------------------------------------
3114 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3115 : _is_complete(Incomplete), _does_not_escape(false),
3116 MemBarNode(C, adr_type, rawoop)
3117 {
3118 init_class_id(Class_Initialize);
3119
3120 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3121 assert(in(RawAddress) == rawoop, "proper init");
3122 // Note: allocation() can be NULL, for secondary initialization barriers
3123 }
3124
3125 // Since this node is not matched, it will be processed by the
3126 // register allocator. Declare that there are no constraints
3127 // on the allocation of the RawAddress edge.
3128 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3129 // This edge should be set to top, by the set_complete. But be conservative.
3130 if (idx == InitializeNode::RawAddress)
3131 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3132 return RegMask::Empty;
3133 }
3134
3135 Node* InitializeNode::memory(uint alias_idx) {
3136 Node* mem = in(Memory);
3137 if (mem->is_MergeMem()) {
3138 return mem->as_MergeMem()->memory_at(alias_idx);
3139 } else {
3140 // incoming raw memory is not split
3141 return mem;
3142 }
3143 }
3144
3145 bool InitializeNode::is_non_zero() {
3146 if (is_complete()) return false;
3147 remove_extra_zeroes();
3148 return (req() > RawStores);
3149 }
3150
3151 void InitializeNode::set_complete(PhaseGVN* phase) {
3152 assert(!is_complete(), "caller responsibility");
3153 _is_complete = Complete;
3154
3155 // After this node is complete, it contains a bunch of
3156 // raw-memory initializations. There is no need for
3157 // it to have anything to do with non-raw memory effects.
3158 // Therefore, tell all non-raw users to re-optimize themselves,
3159 // after skipping the memory effects of this initialization.
3160 PhaseIterGVN* igvn = phase->is_IterGVN();
3161 if (igvn) igvn->add_users_to_worklist(this);
3162 }
3163
3164 // convenience function
3165 // return false if the init contains any stores already
3166 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3167 InitializeNode* init = initialization();
3168 if (init == NULL || init->is_complete()) return false;
3169 init->remove_extra_zeroes();
3170 // for now, if this allocation has already collected any inits, bail:
3171 if (init->is_non_zero()) return false;
3172 init->set_complete(phase);
3173 return true;
3174 }
3175
3176 void InitializeNode::remove_extra_zeroes() {
3177 if (req() == RawStores) return;
3178 Node* zmem = zero_memory();
3179 uint fill = RawStores;
3180 for (uint i = fill; i < req(); i++) {
3181 Node* n = in(i);
3182 if (n->is_top() || n == zmem) continue; // skip
3183 if (fill < i) set_req(fill, n); // compact
3184 ++fill;
3185 }
3186 // delete any empty spaces created:
3187 while (fill < req()) {
3188 del_req(fill);
3189 }
3190 }
3191
3192 // Helper for remembering which stores go with which offsets.
3193 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3194 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3195 intptr_t offset = -1;
3196 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3197 phase, offset);
3198 if (base == NULL) return -1; // something is dead,
3199 if (offset < 0) return -1; // dead, dead
3200 return offset;
3201 }
3202
3203 // Helper for proving that an initialization expression is
3204 // "simple enough" to be folded into an object initialization.
3205 // Attempts to prove that a store's initial value 'n' can be captured
3206 // within the initialization without creating a vicious cycle, such as:
3207 // { Foo p = new Foo(); p.next = p; }
3208 // True for constants and parameters and small combinations thereof.
3209 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3210 if (n == NULL) return true; // (can this really happen?)
3211 if (n->is_Proj()) n = n->in(0);
3212 if (n == this) return false; // found a cycle
3213 if (n->is_Con()) return true;
3214 if (n->is_Start()) return true; // params, etc., are OK
3215 if (n->is_Root()) return true; // even better
3216
3217 Node* ctl = n->in(0);
3218 if (ctl != NULL && !ctl->is_top()) {
3219 if (ctl->is_Proj()) ctl = ctl->in(0);
3220 if (ctl == this) return false;
3221
3222 // If we already know that the enclosing memory op is pinned right after
3223 // the init, then any control flow that the store has picked up
3224 // must have preceded the init, or else be equal to the init.
3225 // Even after loop optimizations (which might change control edges)
3226 // a store is never pinned *before* the availability of its inputs.
3227 if (!MemNode::all_controls_dominate(n, this))
3228 return false; // failed to prove a good control
3229 }
3230
3231 // Check data edges for possible dependencies on 'this'.
3232 if ((count += 1) > 20) return false; // complexity limit
3233 for (uint i = 1; i < n->req(); i++) {
3234 Node* m = n->in(i);
3235 if (m == NULL || m == n || m->is_top()) continue;
3236 uint first_i = n->find_edge(m);
3237 if (i != first_i) continue; // process duplicate edge just once
3238 if (!detect_init_independence(m, count)) {
3239 return false;
3240 }
3241 }
3242
3243 return true;
3244 }
3245
3246 // Here are all the checks a Store must pass before it can be moved into
3247 // an initialization. Returns zero if a check fails.
3248 // On success, returns the (constant) offset to which the store applies,
3249 // within the initialized memory.
3250 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3251 const int FAIL = 0;
3252 if (st->req() != MemNode::ValueIn + 1)
3253 return FAIL; // an inscrutable StoreNode (card mark?)
3254 Node* ctl = st->in(MemNode::Control);
3255 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3256 return FAIL; // must be unconditional after the initialization
3257 Node* mem = st->in(MemNode::Memory);
3258 if (!(mem->is_Proj() && mem->in(0) == this))
3259 return FAIL; // must not be preceded by other stores
3260 Node* adr = st->in(MemNode::Address);
3261 intptr_t offset;
3262 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3263 if (alloc == NULL)
3264 return FAIL; // inscrutable address
3265 if (alloc != allocation())
3266 return FAIL; // wrong allocation! (store needs to float up)
3267 Node* val = st->in(MemNode::ValueIn);
3268 int complexity_count = 0;
3269 if (!detect_init_independence(val, complexity_count))
3270 return FAIL; // stored value must be 'simple enough'
3271
3272 // The Store can be captured only if nothing after the allocation
3273 // and before the Store is using the memory location that the store
3274 // overwrites.
3275 bool failed = false;
3276 // If is_complete_with_arraycopy() is true the shape of the graph is
3277 // well defined and is safe so no need for extra checks.
3278 if (!is_complete_with_arraycopy()) {
3279 // We are going to look at each use of the memory state following
3280 // the allocation to make sure nothing reads the memory that the
3281 // Store writes.
3282 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3283 int alias_idx = phase->C->get_alias_index(t_adr);
3284 ResourceMark rm;
3285 Unique_Node_List mems;
3286 mems.push(mem);
3287 Node* unique_merge = NULL;
3288 for (uint next = 0; next < mems.size(); ++next) {
3289 Node *m = mems.at(next);
3290 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3291 Node *n = m->fast_out(j);
3292 if (n->outcnt() == 0) {
3293 continue;
3294 }
3295 if (n == st) {
3296 continue;
3297 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3298 // If the control of this use is different from the control
3299 // of the Store which is right after the InitializeNode then
3300 // this node cannot be between the InitializeNode and the
3301 // Store.
3302 continue;
3303 } else if (n->is_MergeMem()) {
3304 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3305 // We can hit a MergeMemNode (that will likely go away
3306 // later) that is a direct use of the memory state
3307 // following the InitializeNode on the same slice as the
3308 // store node that we'd like to capture. We need to check
3309 // the uses of the MergeMemNode.
3310 mems.push(n);
3311 }
3312 } else if (n->is_Mem()) {
3313 Node* other_adr = n->in(MemNode::Address);
3314 if (other_adr == adr) {
3315 failed = true;
3316 break;
3317 } else {
3318 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3319 if (other_t_adr != NULL) {
3320 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3321 if (other_alias_idx == alias_idx) {
3322 // A load from the same memory slice as the store right
3323 // after the InitializeNode. We check the control of the
3324 // object/array that is loaded from. If it's the same as
3325 // the store control then we cannot capture the store.
3326 assert(!n->is_Store(), "2 stores to same slice on same control?");
3327 Node* base = other_adr;
3328 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3329 base = base->in(AddPNode::Base);
3330 if (base != NULL) {
3331 base = base->uncast();
3332 if (base->is_Proj() && base->in(0) == alloc) {
3333 failed = true;
3334 break;
3335 }
3336 }
3337 }
3338 }
3339 }
3340 } else {
3341 failed = true;
3342 break;
3343 }
3344 }
3345 }
3346 }
3347 if (failed) {
3348 if (!can_reshape) {
3349 // We decided we couldn't capture the store during parsing. We
3350 // should try again during the next IGVN once the graph is
3351 // cleaner.
3352 phase->C->record_for_igvn(st);
3353 }
3354 return FAIL;
3355 }
3356
3357 return offset; // success
3358 }
3359
3360 // Find the captured store in(i) which corresponds to the range
3361 // [start..start+size) in the initialized object.
3362 // If there is one, return its index i. If there isn't, return the
3363 // negative of the index where it should be inserted.
3364 // Return 0 if the queried range overlaps an initialization boundary
3365 // or if dead code is encountered.
3366 // If size_in_bytes is zero, do not bother with overlap checks.
3367 int InitializeNode::captured_store_insertion_point(intptr_t start,
3368 int size_in_bytes,
3369 PhaseTransform* phase) {
3370 const int FAIL = 0, MAX_STORE = BytesPerLong;
3371
3372 if (is_complete())
3373 return FAIL; // arraycopy got here first; punt
3374
3375 assert(allocation() != NULL, "must be present");
3376
3377 // no negatives, no header fields:
3378 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3379
3380 // after a certain size, we bail out on tracking all the stores:
3381 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3382 if (start >= ti_limit) return FAIL;
3383
3384 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3385 if (i >= limit) return -(int)i; // not found; here is where to put it
3386
3387 Node* st = in(i);
3388 intptr_t st_off = get_store_offset(st, phase);
3389 if (st_off < 0) {
3390 if (st != zero_memory()) {
3391 return FAIL; // bail out if there is dead garbage
3392 }
3393 } else if (st_off > start) {
3394 // ...we are done, since stores are ordered
3395 if (st_off < start + size_in_bytes) {
3396 return FAIL; // the next store overlaps
3397 }
3398 return -(int)i; // not found; here is where to put it
3399 } else if (st_off < start) {
3400 if (size_in_bytes != 0 &&
3401 start < st_off + MAX_STORE &&
3402 start < st_off + st->as_Store()->memory_size()) {
3403 return FAIL; // the previous store overlaps
3404 }
3405 } else {
3406 if (size_in_bytes != 0 &&
3407 st->as_Store()->memory_size() != size_in_bytes) {
3408 return FAIL; // mismatched store size
3409 }
3410 return i;
3411 }
3412
3413 ++i;
3414 }
3415 }
3416
3417 // Look for a captured store which initializes at the offset 'start'
3418 // with the given size. If there is no such store, and no other
3419 // initialization interferes, then return zero_memory (the memory
3420 // projection of the AllocateNode).
3421 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3422 PhaseTransform* phase) {
3423 assert(stores_are_sane(phase), "");
3424 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3425 if (i == 0) {
3426 return NULL; // something is dead
3427 } else if (i < 0) {
3428 return zero_memory(); // just primordial zero bits here
3429 } else {
3430 Node* st = in(i); // here is the store at this position
3431 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3432 return st;
3433 }
3434 }
3435
3436 // Create, as a raw pointer, an address within my new object at 'offset'.
3437 Node* InitializeNode::make_raw_address(intptr_t offset,
3438 PhaseTransform* phase) {
3439 Node* addr = in(RawAddress);
3440 if (offset != 0) {
3441 Compile* C = phase->C;
3442 addr = phase->transform( new AddPNode(C->top(), addr,
3443 phase->MakeConX(offset)) );
3444 }
3445 return addr;
3446 }
3447
3448 // Clone the given store, converting it into a raw store
3449 // initializing a field or element of my new object.
3450 // Caller is responsible for retiring the original store,
3451 // with subsume_node or the like.
3452 //
3453 // From the example above InitializeNode::InitializeNode,
3454 // here are the old stores to be captured:
3455 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3456 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3457 //
3458 // Here is the changed code; note the extra edges on init:
3459 // alloc = (Allocate ...)
3460 // rawoop = alloc.RawAddress
3461 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3462 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3463 // init = (Initialize alloc.Control alloc.Memory rawoop
3464 // rawstore1 rawstore2)
3465 //
3466 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3467 PhaseTransform* phase, bool can_reshape) {
3468 assert(stores_are_sane(phase), "");
3469
3470 if (start < 0) return NULL;
3471 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3472
3473 Compile* C = phase->C;
3474 int size_in_bytes = st->memory_size();
3475 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3476 if (i == 0) return NULL; // bail out
3477 Node* prev_mem = NULL; // raw memory for the captured store
3478 if (i > 0) {
3479 prev_mem = in(i); // there is a pre-existing store under this one
3480 set_req(i, C->top()); // temporarily disconnect it
3481 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3482 } else {
3483 i = -i; // no pre-existing store
3484 prev_mem = zero_memory(); // a slice of the newly allocated object
3485 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3486 set_req(--i, C->top()); // reuse this edge; it has been folded away
3487 else
3488 ins_req(i, C->top()); // build a new edge
3489 }
3490 Node* new_st = st->clone();
3491 new_st->set_req(MemNode::Control, in(Control));
3492 new_st->set_req(MemNode::Memory, prev_mem);
3493 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3494 new_st = phase->transform(new_st);
3495
3496 // At this point, new_st might have swallowed a pre-existing store
3497 // at the same offset, or perhaps new_st might have disappeared,
3498 // if it redundantly stored the same value (or zero to fresh memory).
3499
3500 // In any case, wire it in:
3501 set_req(i, new_st);
3502
3503 // The caller may now kill the old guy.
3504 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3505 assert(check_st == new_st || check_st == NULL, "must be findable");
3506 assert(!is_complete(), "");
3507 return new_st;
3508 }
3509
3510 static bool store_constant(jlong* tiles, int num_tiles,
3511 intptr_t st_off, int st_size,
3512 jlong con) {
3513 if ((st_off & (st_size-1)) != 0)
3514 return false; // strange store offset (assume size==2**N)
3515 address addr = (address)tiles + st_off;
3516 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3517 switch (st_size) {
3518 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3519 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3520 case sizeof(jint): *(jint*) addr = (jint) con; break;
3521 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3522 default: return false; // strange store size (detect size!=2**N here)
3523 }
3524 return true; // return success to caller
3525 }
3526
3527 // Coalesce subword constants into int constants and possibly
3528 // into long constants. The goal, if the CPU permits,
3529 // is to initialize the object with a small number of 64-bit tiles.
3530 // Also, convert floating-point constants to bit patterns.
3531 // Non-constants are not relevant to this pass.
3532 //
3533 // In terms of the running example on InitializeNode::InitializeNode
3534 // and InitializeNode::capture_store, here is the transformation
3535 // of rawstore1 and rawstore2 into rawstore12:
3536 // alloc = (Allocate ...)
3537 // rawoop = alloc.RawAddress
3538 // tile12 = 0x00010002
3539 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3540 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3541 //
3542 void
3543 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3544 Node* size_in_bytes,
3545 PhaseGVN* phase) {
3546 Compile* C = phase->C;
3547
3548 assert(stores_are_sane(phase), "");
3549 // Note: After this pass, they are not completely sane,
3550 // since there may be some overlaps.
3551
3552 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3553
3554 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3555 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3556 size_limit = MIN2(size_limit, ti_limit);
3557 size_limit = align_size_up(size_limit, BytesPerLong);
3558 int num_tiles = size_limit / BytesPerLong;
3559
3560 // allocate space for the tile map:
3561 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3562 jlong tiles_buf[small_len];
3563 Node* nodes_buf[small_len];
3564 jlong inits_buf[small_len];
3565 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3566 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3567 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3568 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3569 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3570 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3571 // tiles: exact bitwise model of all primitive constants
3572 // nodes: last constant-storing node subsumed into the tiles model
3573 // inits: which bytes (in each tile) are touched by any initializations
3574
3575 //// Pass A: Fill in the tile model with any relevant stores.
3576
3577 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3578 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3579 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3580 Node* zmem = zero_memory(); // initially zero memory state
3581 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3582 Node* st = in(i);
3583 intptr_t st_off = get_store_offset(st, phase);
3584
3585 // Figure out the store's offset and constant value:
3586 if (st_off < header_size) continue; //skip (ignore header)
3587 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3588 int st_size = st->as_Store()->memory_size();
3589 if (st_off + st_size > size_limit) break;
3590
3591 // Record which bytes are touched, whether by constant or not.
3592 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3593 continue; // skip (strange store size)
3594
3595 const Type* val = phase->type(st->in(MemNode::ValueIn));
3596 if (!val->singleton()) continue; //skip (non-con store)
3597 BasicType type = val->basic_type();
3598
3599 jlong con = 0;
3600 switch (type) {
3601 case T_INT: con = val->is_int()->get_con(); break;
3602 case T_LONG: con = val->is_long()->get_con(); break;
3603 case T_FLOAT: con = jint_cast(val->getf()); break;
3604 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3605 default: continue; //skip (odd store type)
3606 }
3607
3608 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3609 st->Opcode() == Op_StoreL) {
3610 continue; // This StoreL is already optimal.
3611 }
3612
3613 // Store down the constant.
3614 store_constant(tiles, num_tiles, st_off, st_size, con);
3615
3616 intptr_t j = st_off >> LogBytesPerLong;
3617
3618 if (type == T_INT && st_size == BytesPerInt
3619 && (st_off & BytesPerInt) == BytesPerInt) {
3620 jlong lcon = tiles[j];
3621 if (!Matcher::isSimpleConstant64(lcon) &&
3622 st->Opcode() == Op_StoreI) {
3623 // This StoreI is already optimal by itself.
3624 jint* intcon = (jint*) &tiles[j];
3625 intcon[1] = 0; // undo the store_constant()
3626
3627 // If the previous store is also optimal by itself, back up and
3628 // undo the action of the previous loop iteration... if we can.
3629 // But if we can't, just let the previous half take care of itself.
3630 st = nodes[j];
3631 st_off -= BytesPerInt;
3632 con = intcon[0];
3633 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3634 assert(st_off >= header_size, "still ignoring header");
3635 assert(get_store_offset(st, phase) == st_off, "must be");
3636 assert(in(i-1) == zmem, "must be");
3637 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3638 assert(con == tcon->is_int()->get_con(), "must be");
3639 // Undo the effects of the previous loop trip, which swallowed st:
3640 intcon[0] = 0; // undo store_constant()
3641 set_req(i-1, st); // undo set_req(i, zmem)
3642 nodes[j] = NULL; // undo nodes[j] = st
3643 --old_subword; // undo ++old_subword
3644 }
3645 continue; // This StoreI is already optimal.
3646 }
3647 }
3648
3649 // This store is not needed.
3650 set_req(i, zmem);
3651 nodes[j] = st; // record for the moment
3652 if (st_size < BytesPerLong) // something has changed
3653 ++old_subword; // includes int/float, but who's counting...
3654 else ++old_long;
3655 }
3656
3657 if ((old_subword + old_long) == 0)
3658 return; // nothing more to do
3659
3660 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3661 // Be sure to insert them before overlapping non-constant stores.
3662 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3663 for (int j = 0; j < num_tiles; j++) {
3664 jlong con = tiles[j];
3665 jlong init = inits[j];
3666 if (con == 0) continue;
3667 jint con0, con1; // split the constant, address-wise
3668 jint init0, init1; // split the init map, address-wise
3669 { union { jlong con; jint intcon[2]; } u;
3670 u.con = con;
3671 con0 = u.intcon[0];
3672 con1 = u.intcon[1];
3673 u.con = init;
3674 init0 = u.intcon[0];
3675 init1 = u.intcon[1];
3676 }
3677
3678 Node* old = nodes[j];
3679 assert(old != NULL, "need the prior store");
3680 intptr_t offset = (j * BytesPerLong);
3681
3682 bool split = !Matcher::isSimpleConstant64(con);
3683
3684 if (offset < header_size) {
3685 assert(offset + BytesPerInt >= header_size, "second int counts");
3686 assert(*(jint*)&tiles[j] == 0, "junk in header");
3687 split = true; // only the second word counts
3688 // Example: int a[] = { 42 ... }
3689 } else if (con0 == 0 && init0 == -1) {
3690 split = true; // first word is covered by full inits
3691 // Example: int a[] = { ... foo(), 42 ... }
3692 } else if (con1 == 0 && init1 == -1) {
3693 split = true; // second word is covered by full inits
3694 // Example: int a[] = { ... 42, foo() ... }
3695 }
3696
3697 // Here's a case where init0 is neither 0 nor -1:
3698 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3699 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3700 // In this case the tile is not split; it is (jlong)42.
3701 // The big tile is stored down, and then the foo() value is inserted.
3702 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3703
3704 Node* ctl = old->in(MemNode::Control);
3705 Node* adr = make_raw_address(offset, phase);
3706 const TypePtr* atp = TypeRawPtr::BOTTOM;
3707
3708 // One or two coalesced stores to plop down.
3709 Node* st[2];
3710 intptr_t off[2];
3711 int nst = 0;
3712 if (!split) {
3713 ++new_long;
3714 off[nst] = offset;
3715 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3716 phase->longcon(con), T_LONG, MemNode::unordered);
3717 } else {
3718 // Omit either if it is a zero.
3719 if (con0 != 0) {
3720 ++new_int;
3721 off[nst] = offset;
3722 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3723 phase->intcon(con0), T_INT, MemNode::unordered);
3724 }
3725 if (con1 != 0) {
3726 ++new_int;
3727 offset += BytesPerInt;
3728 adr = make_raw_address(offset, phase);
3729 off[nst] = offset;
3730 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3731 phase->intcon(con1), T_INT, MemNode::unordered);
3732 }
3733 }
3734
3735 // Insert second store first, then the first before the second.
3736 // Insert each one just before any overlapping non-constant stores.
3737 while (nst > 0) {
3738 Node* st1 = st[--nst];
3739 C->copy_node_notes_to(st1, old);
3740 st1 = phase->transform(st1);
3741 offset = off[nst];
3742 assert(offset >= header_size, "do not smash header");
3743 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3744 guarantee(ins_idx != 0, "must re-insert constant store");
3745 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3746 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3747 set_req(--ins_idx, st1);
3748 else
3749 ins_req(ins_idx, st1);
3750 }
3751 }
3752
3753 if (PrintCompilation && WizardMode)
3754 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3755 old_subword, old_long, new_int, new_long);
3756 if (C->log() != NULL)
3757 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3758 old_subword, old_long, new_int, new_long);
3759
3760 // Clean up any remaining occurrences of zmem:
3761 remove_extra_zeroes();
3762 }
3763
3764 // Explore forward from in(start) to find the first fully initialized
3765 // word, and return its offset. Skip groups of subword stores which
3766 // together initialize full words. If in(start) is itself part of a
3767 // fully initialized word, return the offset of in(start). If there
3768 // are no following full-word stores, or if something is fishy, return
3769 // a negative value.
3770 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3771 int int_map = 0;
3772 intptr_t int_map_off = 0;
3773 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3774
3775 for (uint i = start, limit = req(); i < limit; i++) {
3776 Node* st = in(i);
3777
3778 intptr_t st_off = get_store_offset(st, phase);
3779 if (st_off < 0) break; // return conservative answer
3780
3781 int st_size = st->as_Store()->memory_size();
3782 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3783 return st_off; // we found a complete word init
3784 }
3785
3786 // update the map:
3787
3788 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3789 if (this_int_off != int_map_off) {
3790 // reset the map:
3791 int_map = 0;
3792 int_map_off = this_int_off;
3793 }
3794
3795 int subword_off = st_off - this_int_off;
3796 int_map |= right_n_bits(st_size) << subword_off;
3797 if ((int_map & FULL_MAP) == FULL_MAP) {
3798 return this_int_off; // we found a complete word init
3799 }
3800
3801 // Did this store hit or cross the word boundary?
3802 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3803 if (next_int_off == this_int_off + BytesPerInt) {
3804 // We passed the current int, without fully initializing it.
3805 int_map_off = next_int_off;
3806 int_map >>= BytesPerInt;
3807 } else if (next_int_off > this_int_off + BytesPerInt) {
3808 // We passed the current and next int.
3809 return this_int_off + BytesPerInt;
3810 }
3811 }
3812
3813 return -1;
3814 }
3815
3816
3817 // Called when the associated AllocateNode is expanded into CFG.
3818 // At this point, we may perform additional optimizations.
3819 // Linearize the stores by ascending offset, to make memory
3820 // activity as coherent as possible.
3821 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3822 intptr_t header_size,
3823 Node* size_in_bytes,
3824 PhaseGVN* phase) {
3825 assert(!is_complete(), "not already complete");
3826 assert(stores_are_sane(phase), "");
3827 assert(allocation() != NULL, "must be present");
3828
3829 remove_extra_zeroes();
3830
3831 if (ReduceFieldZeroing || ReduceBulkZeroing)
3832 // reduce instruction count for common initialization patterns
3833 coalesce_subword_stores(header_size, size_in_bytes, phase);
3834
3835 Node* zmem = zero_memory(); // initially zero memory state
3836 Node* inits = zmem; // accumulating a linearized chain of inits
3837 #ifdef ASSERT
3838 intptr_t first_offset = allocation()->minimum_header_size();
3839 intptr_t last_init_off = first_offset; // previous init offset
3840 intptr_t last_init_end = first_offset; // previous init offset+size
3841 intptr_t last_tile_end = first_offset; // previous tile offset+size
3842 #endif
3843 intptr_t zeroes_done = header_size;
3844
3845 bool do_zeroing = true; // we might give up if inits are very sparse
3846 int big_init_gaps = 0; // how many large gaps have we seen?
3847
3848 if (ZeroTLAB) do_zeroing = false;
3849 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3850
3851 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3852 Node* st = in(i);
3853 intptr_t st_off = get_store_offset(st, phase);
3854 if (st_off < 0)
3855 break; // unknown junk in the inits
3856 if (st->in(MemNode::Memory) != zmem)
3857 break; // complicated store chains somehow in list
3858
3859 int st_size = st->as_Store()->memory_size();
3860 intptr_t next_init_off = st_off + st_size;
3861
3862 if (do_zeroing && zeroes_done < next_init_off) {
3863 // See if this store needs a zero before it or under it.
3864 intptr_t zeroes_needed = st_off;
3865
3866 if (st_size < BytesPerInt) {
3867 // Look for subword stores which only partially initialize words.
3868 // If we find some, we must lay down some word-level zeroes first,
3869 // underneath the subword stores.
3870 //
3871 // Examples:
3872 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3873 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3874 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3875 //
3876 // Note: coalesce_subword_stores may have already done this,
3877 // if it was prompted by constant non-zero subword initializers.
3878 // But this case can still arise with non-constant stores.
3879
3880 intptr_t next_full_store = find_next_fullword_store(i, phase);
3881
3882 // In the examples above:
3883 // in(i) p q r s x y z
3884 // st_off 12 13 14 15 12 13 14
3885 // st_size 1 1 1 1 1 1 1
3886 // next_full_s. 12 16 16 16 16 16 16
3887 // z's_done 12 16 16 16 12 16 12
3888 // z's_needed 12 16 16 16 16 16 16
3889 // zsize 0 0 0 0 4 0 4
3890 if (next_full_store < 0) {
3891 // Conservative tack: Zero to end of current word.
3892 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3893 } else {
3894 // Zero to beginning of next fully initialized word.
3895 // Or, don't zero at all, if we are already in that word.
3896 assert(next_full_store >= zeroes_needed, "must go forward");
3897 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3898 zeroes_needed = next_full_store;
3899 }
3900 }
3901
3902 if (zeroes_needed > zeroes_done) {
3903 intptr_t zsize = zeroes_needed - zeroes_done;
3904 // Do some incremental zeroing on rawmem, in parallel with inits.
3905 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3906 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3907 zeroes_done, zeroes_needed,
3908 phase);
3909 zeroes_done = zeroes_needed;
3910 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3911 do_zeroing = false; // leave the hole, next time
3912 }
3913 }
3914
3915 // Collect the store and move on:
3916 st->set_req(MemNode::Memory, inits);
3917 inits = st; // put it on the linearized chain
3918 set_req(i, zmem); // unhook from previous position
3919
3920 if (zeroes_done == st_off)
3921 zeroes_done = next_init_off;
3922
3923 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3924
3925 #ifdef ASSERT
3926 // Various order invariants. Weaker than stores_are_sane because
3927 // a large constant tile can be filled in by smaller non-constant stores.
3928 assert(st_off >= last_init_off, "inits do not reverse");
3929 last_init_off = st_off;
3930 const Type* val = NULL;
3931 if (st_size >= BytesPerInt &&
3932 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3933 (int)val->basic_type() < (int)T_OBJECT) {
3934 assert(st_off >= last_tile_end, "tiles do not overlap");
3935 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3936 last_tile_end = MAX2(last_tile_end, next_init_off);
3937 } else {
3938 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3939 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3940 assert(st_off >= last_init_end, "inits do not overlap");
3941 last_init_end = next_init_off; // it's a non-tile
3942 }
3943 #endif //ASSERT
3944 }
3945
3946 remove_extra_zeroes(); // clear out all the zmems left over
3947 add_req(inits);
3948
3949 if (!ZeroTLAB) {
3950 // If anything remains to be zeroed, zero it all now.
3951 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3952 // if it is the last unused 4 bytes of an instance, forget about it
3953 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3954 if (zeroes_done + BytesPerLong >= size_limit) {
3955 assert(allocation() != NULL, "");
3956 if (allocation()->Opcode() == Op_Allocate) {
3957 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3958 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3959 if (zeroes_done == k->layout_helper())
3960 zeroes_done = size_limit;
3961 }
3962 }
3963 if (zeroes_done < size_limit) {
3964 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3965 zeroes_done, size_in_bytes, phase);
3966 }
3967 }
3968
3969 set_complete(phase);
3970 return rawmem;
3971 }
3972
3973
3974 #ifdef ASSERT
3975 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3976 if (is_complete())
3977 return true; // stores could be anything at this point
3978 assert(allocation() != NULL, "must be present");
3979 intptr_t last_off = allocation()->minimum_header_size();
3980 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3981 Node* st = in(i);
3982 intptr_t st_off = get_store_offset(st, phase);
3983 if (st_off < 0) continue; // ignore dead garbage
3984 if (last_off > st_off) {
3985 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
3986 this->dump(2);
3987 assert(false, "ascending store offsets");
3988 return false;
3989 }
3990 last_off = st_off + st->as_Store()->memory_size();
3991 }
3992 return true;
3993 }
3994 #endif //ASSERT
3995
3996
3997
3998
3999 //============================MergeMemNode=====================================
4000 //
4001 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4002 // contributing store or call operations. Each contributor provides the memory
4003 // state for a particular "alias type" (see Compile::alias_type). For example,
4004 // if a MergeMem has an input X for alias category #6, then any memory reference
4005 // to alias category #6 may use X as its memory state input, as an exact equivalent
4006 // to using the MergeMem as a whole.
4007 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4008 //
4009 // (Here, the <N> notation gives the index of the relevant adr_type.)
4010 //
4011 // In one special case (and more cases in the future), alias categories overlap.
4012 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4013 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4014 // it is exactly equivalent to that state W:
4015 // MergeMem(<Bot>: W) <==> W
4016 //
4017 // Usually, the merge has more than one input. In that case, where inputs
4018 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4019 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4020 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4021 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4022 //
4023 // A merge can take a "wide" memory state as one of its narrow inputs.
4024 // This simply means that the merge observes out only the relevant parts of
4025 // the wide input. That is, wide memory states arriving at narrow merge inputs
4026 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4027 //
4028 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4029 // and that memory slices "leak through":
4030 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4031 //
4032 // But, in such a cascade, repeated memory slices can "block the leak":
4033 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4034 //
4035 // In the last example, Y is not part of the combined memory state of the
4036 // outermost MergeMem. The system must, of course, prevent unschedulable
4037 // memory states from arising, so you can be sure that the state Y is somehow
4038 // a precursor to state Y'.
4039 //
4040 //
4041 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4042 // of each MergeMemNode array are exactly the numerical alias indexes, including
4043 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4044 // Compile::alias_type (and kin) produce and manage these indexes.
4045 //
4046 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4047 // (Note that this provides quick access to the top node inside MergeMem methods,
4048 // without the need to reach out via TLS to Compile::current.)
4049 //
4050 // As a consequence of what was just described, a MergeMem that represents a full
4051 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4052 // containing all alias categories.
4053 //
4054 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4055 //
4056 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4057 // a memory state for the alias type <N>, or else the top node, meaning that
4058 // there is no particular input for that alias type. Note that the length of
4059 // a MergeMem is variable, and may be extended at any time to accommodate new
4060 // memory states at larger alias indexes. When merges grow, they are of course
4061 // filled with "top" in the unused in() positions.
4062 //
4063 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4064 // (Top was chosen because it works smoothly with passes like GCM.)
4065 //
4066 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4067 // the type of random VM bits like TLS references.) Since it is always the
4068 // first non-Bot memory slice, some low-level loops use it to initialize an
4069 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4070 //
4071 //
4072 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4073 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4074 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4075 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4076 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4077 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4078 //
4079 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4080 // really that different from the other memory inputs. An abbreviation called
4081 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4082 //
4083 //
4084 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4085 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4086 // that "emerges though" the base memory will be marked as excluding the alias types
4087 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4088 //
4089 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4090 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4091 //
4092 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4093 // (It is currently unimplemented.) As you can see, the resulting merge is
4094 // actually a disjoint union of memory states, rather than an overlay.
4095 //
4096
4097 //------------------------------MergeMemNode-----------------------------------
4098 Node* MergeMemNode::make_empty_memory() {
4099 Node* empty_memory = (Node*) Compile::current()->top();
4100 assert(empty_memory->is_top(), "correct sentinel identity");
4101 return empty_memory;
4102 }
4103
4104 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4105 init_class_id(Class_MergeMem);
4106 // all inputs are nullified in Node::Node(int)
4107 // set_input(0, NULL); // no control input
4108
4109 // Initialize the edges uniformly to top, for starters.
4110 Node* empty_mem = make_empty_memory();
4111 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4112 init_req(i,empty_mem);
4113 }
4114 assert(empty_memory() == empty_mem, "");
4115
4116 if( new_base != NULL && new_base->is_MergeMem() ) {
4117 MergeMemNode* mdef = new_base->as_MergeMem();
4118 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4119 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4120 mms.set_memory(mms.memory2());
4121 }
4122 assert(base_memory() == mdef->base_memory(), "");
4123 } else {
4124 set_base_memory(new_base);
4125 }
4126 }
4127
4128 // Make a new, untransformed MergeMem with the same base as 'mem'.
4129 // If mem is itself a MergeMem, populate the result with the same edges.
4130 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
4131 return new MergeMemNode(mem);
4132 }
4133
4134 //------------------------------cmp--------------------------------------------
4135 uint MergeMemNode::hash() const { return NO_HASH; }
4136 uint MergeMemNode::cmp( const Node &n ) const {
4137 return (&n == this); // Always fail except on self
4138 }
4139
4140 //------------------------------Identity---------------------------------------
4141 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4142 // Identity if this merge point does not record any interesting memory
4143 // disambiguations.
4144 Node* base_mem = base_memory();
4145 Node* empty_mem = empty_memory();
4146 if (base_mem != empty_mem) { // Memory path is not dead?
4147 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4148 Node* mem = in(i);
4149 if (mem != empty_mem && mem != base_mem) {
4150 return this; // Many memory splits; no change
4151 }
4152 }
4153 }
4154 return base_mem; // No memory splits; ID on the one true input
4155 }
4156
4157 //------------------------------Ideal------------------------------------------
4158 // This method is invoked recursively on chains of MergeMem nodes
4159 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4160 // Remove chain'd MergeMems
4161 //
4162 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4163 // relative to the "in(Bot)". Since we are patching both at the same time,
4164 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4165 // but rewrite each "in(i)" relative to the new "in(Bot)".
4166 Node *progress = NULL;
4167
4168
4169 Node* old_base = base_memory();
4170 Node* empty_mem = empty_memory();
4171 if (old_base == empty_mem)
4172 return NULL; // Dead memory path.
4173
4174 MergeMemNode* old_mbase;
4175 if (old_base != NULL && old_base->is_MergeMem())
4176 old_mbase = old_base->as_MergeMem();
4177 else
4178 old_mbase = NULL;
4179 Node* new_base = old_base;
4180
4181 // simplify stacked MergeMems in base memory
4182 if (old_mbase) new_base = old_mbase->base_memory();
4183
4184 // the base memory might contribute new slices beyond my req()
4185 if (old_mbase) grow_to_match(old_mbase);
4186
4187 // Look carefully at the base node if it is a phi.
4188 PhiNode* phi_base;
4189 if (new_base != NULL && new_base->is_Phi())
4190 phi_base = new_base->as_Phi();
4191 else
4192 phi_base = NULL;
4193
4194 Node* phi_reg = NULL;
4195 uint phi_len = (uint)-1;
4196 if (phi_base != NULL && !phi_base->is_copy()) {
4197 // do not examine phi if degraded to a copy
4198 phi_reg = phi_base->region();
4199 phi_len = phi_base->req();
4200 // see if the phi is unfinished
4201 for (uint i = 1; i < phi_len; i++) {
4202 if (phi_base->in(i) == NULL) {
4203 // incomplete phi; do not look at it yet!
4204 phi_reg = NULL;
4205 phi_len = (uint)-1;
4206 break;
4207 }
4208 }
4209 }
4210
4211 // Note: We do not call verify_sparse on entry, because inputs
4212 // can normalize to the base_memory via subsume_node or similar
4213 // mechanisms. This method repairs that damage.
4214
4215 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4216
4217 // Look at each slice.
4218 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4219 Node* old_in = in(i);
4220 // calculate the old memory value
4221 Node* old_mem = old_in;
4222 if (old_mem == empty_mem) old_mem = old_base;
4223 assert(old_mem == memory_at(i), "");
4224
4225 // maybe update (reslice) the old memory value
4226
4227 // simplify stacked MergeMems
4228 Node* new_mem = old_mem;
4229 MergeMemNode* old_mmem;
4230 if (old_mem != NULL && old_mem->is_MergeMem())
4231 old_mmem = old_mem->as_MergeMem();
4232 else
4233 old_mmem = NULL;
4234 if (old_mmem == this) {
4235 // This can happen if loops break up and safepoints disappear.
4236 // A merge of BotPtr (default) with a RawPtr memory derived from a
4237 // safepoint can be rewritten to a merge of the same BotPtr with
4238 // the BotPtr phi coming into the loop. If that phi disappears
4239 // also, we can end up with a self-loop of the mergemem.
4240 // In general, if loops degenerate and memory effects disappear,
4241 // a mergemem can be left looking at itself. This simply means
4242 // that the mergemem's default should be used, since there is
4243 // no longer any apparent effect on this slice.
4244 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4245 // from start. Update the input to TOP.
4246 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4247 }
4248 else if (old_mmem != NULL) {
4249 new_mem = old_mmem->memory_at(i);
4250 }
4251 // else preceding memory was not a MergeMem
4252
4253 // replace equivalent phis (unfortunately, they do not GVN together)
4254 if (new_mem != NULL && new_mem != new_base &&
4255 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4256 if (new_mem->is_Phi()) {
4257 PhiNode* phi_mem = new_mem->as_Phi();
4258 for (uint i = 1; i < phi_len; i++) {
4259 if (phi_base->in(i) != phi_mem->in(i)) {
4260 phi_mem = NULL;
4261 break;
4262 }
4263 }
4264 if (phi_mem != NULL) {
4265 // equivalent phi nodes; revert to the def
4266 new_mem = new_base;
4267 }
4268 }
4269 }
4270
4271 // maybe store down a new value
4272 Node* new_in = new_mem;
4273 if (new_in == new_base) new_in = empty_mem;
4274
4275 if (new_in != old_in) {
4276 // Warning: Do not combine this "if" with the previous "if"
4277 // A memory slice might have be be rewritten even if it is semantically
4278 // unchanged, if the base_memory value has changed.
4279 set_req(i, new_in);
4280 progress = this; // Report progress
4281 }
4282 }
4283
4284 if (new_base != old_base) {
4285 set_req(Compile::AliasIdxBot, new_base);
4286 // Don't use set_base_memory(new_base), because we need to update du.
4287 assert(base_memory() == new_base, "");
4288 progress = this;
4289 }
4290
4291 if( base_memory() == this ) {
4292 // a self cycle indicates this memory path is dead
4293 set_req(Compile::AliasIdxBot, empty_mem);
4294 }
4295
4296 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4297 // Recursion must occur after the self cycle check above
4298 if( base_memory()->is_MergeMem() ) {
4299 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4300 Node *m = phase->transform(new_mbase); // Rollup any cycles
4301 if( m != NULL && (m->is_top() ||
4302 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4303 // propagate rollup of dead cycle to self
4304 set_req(Compile::AliasIdxBot, empty_mem);
4305 }
4306 }
4307
4308 if( base_memory() == empty_mem ) {
4309 progress = this;
4310 // Cut inputs during Parse phase only.
4311 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4312 if( !can_reshape ) {
4313 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4314 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4315 }
4316 }
4317 }
4318
4319 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4320 // Check if PhiNode::Ideal's "Split phis through memory merges"
4321 // transform should be attempted. Look for this->phi->this cycle.
4322 uint merge_width = req();
4323 if (merge_width > Compile::AliasIdxRaw) {
4324 PhiNode* phi = base_memory()->as_Phi();
4325 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4326 if (phi->in(i) == this) {
4327 phase->is_IterGVN()->_worklist.push(phi);
4328 break;
4329 }
4330 }
4331 }
4332 }
4333
4334 assert(progress || verify_sparse(), "please, no dups of base");
4335 return progress;
4336 }
4337
4338 //-------------------------set_base_memory-------------------------------------
4339 void MergeMemNode::set_base_memory(Node *new_base) {
4340 Node* empty_mem = empty_memory();
4341 set_req(Compile::AliasIdxBot, new_base);
4342 assert(memory_at(req()) == new_base, "must set default memory");
4343 // Clear out other occurrences of new_base:
4344 if (new_base != empty_mem) {
4345 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4346 if (in(i) == new_base) set_req(i, empty_mem);
4347 }
4348 }
4349 }
4350
4351 //------------------------------out_RegMask------------------------------------
4352 const RegMask &MergeMemNode::out_RegMask() const {
4353 return RegMask::Empty;
4354 }
4355
4356 //------------------------------dump_spec--------------------------------------
4357 #ifndef PRODUCT
4358 void MergeMemNode::dump_spec(outputStream *st) const {
4359 st->print(" {");
4360 Node* base_mem = base_memory();
4361 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4362 Node* mem = memory_at(i);
4363 if (mem == base_mem) { st->print(" -"); continue; }
4364 st->print( " N%d:", mem->_idx );
4365 Compile::current()->get_adr_type(i)->dump_on(st);
4366 }
4367 st->print(" }");
4368 }
4369 #endif // !PRODUCT
4370
4371
4372 #ifdef ASSERT
4373 static bool might_be_same(Node* a, Node* b) {
4374 if (a == b) return true;
4375 if (!(a->is_Phi() || b->is_Phi())) return false;
4376 // phis shift around during optimization
4377 return true; // pretty stupid...
4378 }
4379
4380 // verify a narrow slice (either incoming or outgoing)
4381 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4382 if (!VerifyAliases) return; // don't bother to verify unless requested
4383 if (is_error_reported()) return; // muzzle asserts when debugging an error
4384 if (Node::in_dump()) return; // muzzle asserts when printing
4385 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4386 assert(n != NULL, "");
4387 // Elide intervening MergeMem's
4388 while (n->is_MergeMem()) {
4389 n = n->as_MergeMem()->memory_at(alias_idx);
4390 }
4391 Compile* C = Compile::current();
4392 const TypePtr* n_adr_type = n->adr_type();
4393 if (n == m->empty_memory()) {
4394 // Implicit copy of base_memory()
4395 } else if (n_adr_type != TypePtr::BOTTOM) {
4396 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4397 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4398 } else {
4399 // A few places like make_runtime_call "know" that VM calls are narrow,
4400 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4401 bool expected_wide_mem = false;
4402 if (n == m->base_memory()) {
4403 expected_wide_mem = true;
4404 } else if (alias_idx == Compile::AliasIdxRaw ||
4405 n == m->memory_at(Compile::AliasIdxRaw)) {
4406 expected_wide_mem = true;
4407 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4408 // memory can "leak through" calls on channels that
4409 // are write-once. Allow this also.
4410 expected_wide_mem = true;
4411 }
4412 assert(expected_wide_mem, "expected narrow slice replacement");
4413 }
4414 }
4415 #else // !ASSERT
4416 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4417 #endif
4418
4419
4420 //-----------------------------memory_at---------------------------------------
4421 Node* MergeMemNode::memory_at(uint alias_idx) const {
4422 assert(alias_idx >= Compile::AliasIdxRaw ||
4423 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4424 "must avoid base_memory and AliasIdxTop");
4425
4426 // Otherwise, it is a narrow slice.
4427 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4428 Compile *C = Compile::current();
4429 if (is_empty_memory(n)) {
4430 // the array is sparse; empty slots are the "top" node
4431 n = base_memory();
4432 assert(Node::in_dump()
4433 || n == NULL || n->bottom_type() == Type::TOP
4434 || n->adr_type() == NULL // address is TOP
4435 || n->adr_type() == TypePtr::BOTTOM
4436 || n->adr_type() == TypeRawPtr::BOTTOM
4437 || Compile::current()->AliasLevel() == 0,
4438 "must be a wide memory");
4439 // AliasLevel == 0 if we are organizing the memory states manually.
4440 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4441 } else {
4442 // make sure the stored slice is sane
4443 #ifdef ASSERT
4444 if (is_error_reported() || Node::in_dump()) {
4445 } else if (might_be_same(n, base_memory())) {
4446 // Give it a pass: It is a mostly harmless repetition of the base.
4447 // This can arise normally from node subsumption during optimization.
4448 } else {
4449 verify_memory_slice(this, alias_idx, n);
4450 }
4451 #endif
4452 }
4453 return n;
4454 }
4455
4456 //---------------------------set_memory_at-------------------------------------
4457 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4458 verify_memory_slice(this, alias_idx, n);
4459 Node* empty_mem = empty_memory();
4460 if (n == base_memory()) n = empty_mem; // collapse default
4461 uint need_req = alias_idx+1;
4462 if (req() < need_req) {
4463 if (n == empty_mem) return; // already the default, so do not grow me
4464 // grow the sparse array
4465 do {
4466 add_req(empty_mem);
4467 } while (req() < need_req);
4468 }
4469 set_req( alias_idx, n );
4470 }
4471
4472
4473
4474 //--------------------------iteration_setup------------------------------------
4475 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4476 if (other != NULL) {
4477 grow_to_match(other);
4478 // invariant: the finite support of mm2 is within mm->req()
4479 #ifdef ASSERT
4480 for (uint i = req(); i < other->req(); i++) {
4481 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4482 }
4483 #endif
4484 }
4485 // Replace spurious copies of base_memory by top.
4486 Node* base_mem = base_memory();
4487 if (base_mem != NULL && !base_mem->is_top()) {
4488 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4489 if (in(i) == base_mem)
4490 set_req(i, empty_memory());
4491 }
4492 }
4493 }
4494
4495 //---------------------------grow_to_match-------------------------------------
4496 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4497 Node* empty_mem = empty_memory();
4498 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4499 // look for the finite support of the other memory
4500 for (uint i = other->req(); --i >= req(); ) {
4501 if (other->in(i) != empty_mem) {
4502 uint new_len = i+1;
4503 while (req() < new_len) add_req(empty_mem);
4504 break;
4505 }
4506 }
4507 }
4508
4509 //---------------------------verify_sparse-------------------------------------
4510 #ifndef PRODUCT
4511 bool MergeMemNode::verify_sparse() const {
4512 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4513 Node* base_mem = base_memory();
4514 // The following can happen in degenerate cases, since empty==top.
4515 if (is_empty_memory(base_mem)) return true;
4516 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4517 assert(in(i) != NULL, "sane slice");
4518 if (in(i) == base_mem) return false; // should have been the sentinel value!
4519 }
4520 return true;
4521 }
4522
4523 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4524 Node* n;
4525 n = mm->in(idx);
4526 if (mem == n) return true; // might be empty_memory()
4527 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4528 if (mem == n) return true;
4529 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4530 if (mem == n) return true;
4531 if (n == NULL) break;
4532 }
4533 return false;
4534 }
4535 #endif // !PRODUCT